SQLAlchemy 1.3 Documentation

Using More Specific Text with table(), _expression.literal_column(), and _expression.column()

type_coerce() - an alternative to CAST that coerces the type on the Python side only, which is often sufficient to generate the correct SQL and data coercion.

function sqlalchemy.sql.expression.column(text, type_=None, is_literal=False, _selectable=None)¶

Produce a ColumnClause object.

The ColumnClause is a lightweight analogue to the Column class. The column() function can be invoked with just a name alone, as in:

from sqlalchemy import column

id, name = column("id"), column("name")
stmt = select([id, name]).select_from("user")

The above statement would produce SQL like:

SELECT id, name FROM user

Once constructed, column() may be used like any other SQL expression element such as within select() constructs:

from sqlalchemy.sql import column

id, name = column("id"), column("name")
stmt = select([id, name]).select_from("user")

The text handled by column() is assumed to be handled like the name of a database column; if the string contains mixed case, special characters, or matches a known reserved word on the target backend, the column expression will render using the quoting behavior determined by the backend. To produce a textual SQL expression that is rendered exactly without any quoting, use literal_column() instead, or pass True as the value of column.is_literal. Additionally, full SQL statements are best handled using the text() construct.

column() can be used in a table-like fashion by combining it with the table() function (which is the lightweight analogue to Table ) to produce a working table construct with minimal boilerplate:

from sqlalchemy import table, column, select

user = table("user",
        column("id"),
        column("name"),
        column("description"),
)

stmt = select([user.c.description]).where(user.c.name == 'wendy')

A column() / table() construct like that illustrated above can be created in an ad-hoc fashion and is not associated with any MetaData, DDL, or events, unlike its Table counterpart.

Changed in version 1.0.0: column() can now be imported from the plain sqlalchemy namespace like any other SQL element.

Parameters:

text¶ – the text of the element.
type¶ – TypeEngine object which can associate this ColumnClause with a type.
is_literal¶ – if True, the ColumnClause is assumed to be an exact expression that will be delivered to the output with no quoting rules applied regardless of case sensitive settings. the literal_column() function essentially invokes column() while passing is_literal=True.

See also

function sqlalchemy.sql.expression.collate(expression, collation)¶

Return the clause expression COLLATE collation.

e.g.:

collate(mycolumn, 'utf8_bin')

produces:

mycolumn COLLATE utf8_bin

The collation expression is also quoted if it is a case sensitive identifier, e.g. contains uppercase characters.

Changed in version 1.2: quoting is automatically applied to COLLATE expressions if they are case sensitive.

function sqlalchemy.sql.expression.desc(column)¶

Produce a descending ORDER BY clause element.

e.g.:

from sqlalchemy import desc

stmt = select([users_table]).order_by(desc(users_table.c.name))

will produce SQL as:

SELECT id, name FROM user ORDER BY name DESC

The desc() function is a standalone version of the ColumnElement.desc() method available on all SQL expressions, e.g.:

stmt = select([users_table]).order_by(users_table.c.name.desc())

Parameters:: column¶ – A ColumnElement (e.g. scalar SQL expression) with which to apply the desc() operation.

See also

function sqlalchemy.sql.expression.distinct(expr)¶

Produce an column-expression-level unary DISTINCT clause.

This applies the DISTINCT keyword to an individual column expression, and is typically contained within an aggregate function, as in:

from sqlalchemy import distinct, func
stmt = select([func.count(distinct(users_table.c.name))])

The above would produce an expression resembling:

SELECT COUNT(DISTINCT name) FROM user

The distinct() function is also available as a column-level method, e.g. ColumnElement.distinct(), as in:

stmt = select([func.count(users_table.c.name.distinct())])

The distinct() operator is different from the Select.distinct() method of Select, which produces a SELECT statement with DISTINCT applied to the result set as a whole, e.g. a SELECT DISTINCT expression. See that method for further information.

See also

ColumnElement.distinct()

Select.distinct()

func

function sqlalchemy.sql.expression.extract(field, expr, **kwargs)¶

Return a Extract construct.

This is typically available as extract() as well as func.extract from the func namespace.

function sqlalchemy.sql.expression.false()¶

Return a False_ construct.

E.g.:

>>> from sqlalchemy import false
>>> print(select([t.c.x]).where(false()))
SELECT x FROM t WHERE false

A backend which does not support true/false constants will render as an expression against 1 or 0:

>>> print(select([t.c.x]).where(false()))
SELECT x FROM t WHERE 0 = 1

The true() and false() constants also feature “short circuit” operation within an and_() or or_() conjunction:

>>> print(select([t.c.x]).where(or_(t.c.x > 5, true())))
SELECT x FROM t WHERE true

>>> print(select([t.c.x]).where(and_(t.c.x > 5, false())))
SELECT x FROM t WHERE false

Changed in version 0.9: true() and false() feature better integrated behavior within conjunctions and on dialects that don’t support true/false constants.

See also

true()

sqlalchemy.sql.expression.func = <sqlalchemy.sql.functions._FunctionGenerator object>¶

Generate SQL function expressions.

func is a special object instance which generates SQL functions based on name-based attributes, e.g.:

>>> print(func.count(1))
count(:param_1)

The returned object is an instance of Function, and is a column-oriented SQL element like any other, and is used in that way:

>>> print(select([func.count(table.c.id)]))
SELECT count(sometable.id) FROM sometable

Any name can be given to func. If the function name is unknown to SQLAlchemy, it will be rendered exactly as is. For common SQL functions which SQLAlchemy is aware of, the name may be interpreted as a generic function which will be compiled appropriately to the target database:

>>> print(func.current_timestamp())
CURRENT_TIMESTAMP

To call functions which are present in dot-separated packages, specify them in the same manner:

>>> print(func.stats.yield_curve(5, 10))
stats.yield_curve(:yield_curve_1, :yield_curve_2)

SQLAlchemy can be made aware of the return type of functions to enable type-specific lexical and result-based behavior. For example, to ensure that a string-based function returns a Unicode value and is similarly treated as a string in expressions, specify Unicode as the type:

>>> print(func.my_string(u'hi', type_=Unicode) + ' ' +
...       func.my_string(u'there', type_=Unicode))
my_string(:my_string_1) || :my_string_2 || my_string(:my_string_3)

The object returned by a func call is usually an instance of Function. This object meets the “column” interface, including comparison and labeling functions. The object can also be passed the Connectable.execute() method of a Connection or Engine, where it will be wrapped inside of a SELECT statement first:

print(connection.execute(func.current_timestamp()).scalar())

In a few exception cases, the func accessor will redirect a name to a built-in expression such as cast() or extract(), as these names have well-known meaning but are not exactly the same as “functions” from a SQLAlchemy perspective.

Functions which are interpreted as “generic” functions know how to calculate their return type automatically. For a listing of known generic functions, see SQL and Generic Functions.

Note

The func construct has only limited support for calling standalone “stored procedures”, especially those with special parameterization concerns.

See the section Calling Stored Procedures for details on how to use the DBAPI-level callproc() method for fully traditional stored procedures.

See also

Functions - in the Core Tutorial

Function

function sqlalchemy.sql.expression.funcfilter(func, *criterion)¶

Produce a FunctionFilter object against a function.

Used against aggregate and window functions, for database backends that support the “FILTER” clause.

E.g.:

from sqlalchemy import funcfilter
funcfilter(func.count(1), MyClass.name == 'some name')

Would produce “COUNT(1) FILTER (WHERE myclass.name = ‘some name’)”.

This function is also available from the func construct itself via the FunctionElement.filter() method.

New in version 1.0.0.

See also

FunctionElement.filter()

function sqlalchemy.sql.expression.label(name, element, type_=None)¶

Return a Label object for the given ColumnElement.

A label changes the name of an element in the columns clause of a SELECT statement, typically via the AS SQL keyword.

This functionality is more conveniently available via the ColumnElement.label() method on ColumnElement.

Parameters:

name¶ – label name
obj¶ – a ColumnElement.

function sqlalchemy.sql.expression.literal(value, type_=None)¶

Return a literal clause, bound to a bind parameter.

Literal clauses are created automatically when non- ClauseElement objects (such as strings, ints, dates, etc.) are used in a comparison operation with a ColumnElement subclass, such as a Column object. Use this function to force the generation of a literal clause, which will be created as a BindParameter with a bound value.

Parameters:

value¶ – the value to be bound. Can be any Python object supported by the underlying DB-API, or is translatable via the given type argument.
type_¶ – an optional TypeEngine which will provide bind-parameter translation for this literal.

function sqlalchemy.sql.expression.literal_column(text, type_=None)¶

Produce a ColumnClause object that has the column.is_literal flag set to True.

literal_column() is similar to column(), except that it is more often used as a “standalone” column expression that renders exactly as stated; while column() stores a string name that will be assumed to be part of a table and may be quoted as such, literal_column() can be that, or any other arbitrary column-oriented expression.

Parameters:

text¶ – the text of the expression; can be any SQL expression. Quoting rules will not be applied. To specify a column-name expression which should be subject to quoting rules, use the column() function.
type_¶ – an optional TypeEngine object which will provide result-set translation and additional expression semantics for this column. If left as None the type will be NullType.

See also

column()

text()

Using More Specific Text with table(), _expression.literal_column(), and _expression.column()

function sqlalchemy.sql.expression.not_(clause)¶

Return a negation of the given clause, i.e. NOT(clause).

The ~ operator is also overloaded on all ColumnElement subclasses to produce the same result.

function sqlalchemy.sql.expression.null()¶: Return a constant Null construct.

function sqlalchemy.sql.expression.nullsfirst(column)¶

Produce the NULLS FIRST modifier for an ORDER BY expression.

nullsfirst() is intended to modify the expression produced by asc() or desc(), and indicates how NULL values should be handled when they are encountered during ordering:

from sqlalchemy import desc, nullsfirst

stmt = select([users_table]).order_by(
    nullsfirst(desc(users_table.c.name)))

The SQL expression from the above would resemble:

SELECT id, name FROM user ORDER BY name DESC NULLS FIRST

Like asc() and desc(), nullsfirst() is typically invoked from the column expression itself using ColumnElement.nullsfirst(), rather than as its standalone function version, as in:

stmt = select([users_table]).order_by(
    users_table.c.name.desc().nullsfirst())

See also

function sqlalchemy.sql.expression.nullslast(column)¶

Produce the NULLS LAST modifier for an ORDER BY expression.

nullslast() is intended to modify the expression produced by asc() or desc(), and indicates how NULL values should be handled when they are encountered during ordering:

from sqlalchemy import desc, nullslast

stmt = select([users_table]).order_by(
    nullslast(desc(users_table.c.name)))

The SQL expression from the above would resemble:

SELECT id, name FROM user ORDER BY name DESC NULLS LAST

Like asc() and desc(), nullslast() is typically invoked from the column expression itself using ColumnElement.nullslast(), rather than as its standalone function version, as in:

stmt = select([users_table]).order_by(
    users_table.c.name.desc().nullslast())

See also

function sqlalchemy.sql.expression.or_(*clauses)¶

Produce a conjunction of expressions joined by OR.

E.g.:

from sqlalchemy import or_

stmt = select([users_table]).where(
                or_(
                    users_table.c.name == 'wendy',
                    users_table.c.name == 'jack'
                )
            )

The or_() conjunction is also available using the Python | operator (though note that compound expressions need to be parenthesized in order to function with Python operator precedence behavior):

stmt = select([users_table]).where(
                (users_table.c.name == 'wendy') |
                (users_table.c.name == 'jack')
            )

See also

and_()

function sqlalchemy.sql.expression.outparam(key, type_=None)¶

Create an ‘OUT’ parameter for usage in functions (stored procedures), for databases which support them.

The outparam can be used like a regular function parameter. The “output” value will be available from the ResultProxy object via its out_parameters attribute, which returns a dictionary containing the values.

function sqlalchemy.sql.expression.over(element, partition_by=None, order_by=None, range_=None, rows=None)¶

Produce an Over object against a function.

Used against aggregate or so-called “window” functions, for database backends that support window functions.

over() is usually called using the FunctionElement.over() method, e.g.:

func.row_number().over(order_by=mytable.c.some_column)

Would produce:

ROW_NUMBER() OVER(ORDER BY some_column)

Ranges are also possible using the over.range_ and over.rows parameters. These mutually-exclusive parameters each accept a 2-tuple, which contains a combination of integers and None:

func.row_number().over(
    order_by=my_table.c.some_column, range_=(None, 0))

The above would produce:

ROW_NUMBER() OVER(ORDER BY some_column
RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)

A value of None indicates “unbounded”, a value of zero indicates “current row”, and negative / positive integers indicate “preceding” and “following”:

RANGE BETWEEN 5 PRECEDING AND 10 FOLLOWING:

func.row_number().over(order_by='x', range_=(-5, 10))

ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW:

func.row_number().over(order_by='x', rows=(None, 0))

RANGE BETWEEN 2 PRECEDING AND UNBOUNDED FOLLOWING:

func.row_number().over(order_by='x', range_=(-2, None))

RANGE BETWEEN 1 FOLLOWING AND 3 FOLLOWING:

func.row_number().over(order_by='x', range_=(1, 3))

New in version 1.1: support for RANGE / ROWS within a window

Parameters:

element¶ – a FunctionElement, WithinGroup, or other compatible construct.
partition_by¶ – a column element or string, or a list of such, that will be used as the PARTITION BY clause of the OVER construct.
order_by¶ – a column element or string, or a list of such, that will be used as the ORDER BY clause of the OVER construct.
range_¶ –
optional range clause for the window. This is a tuple value which can contain integer values or None, and will render a RANGE BETWEEN PRECEDING / FOLLOWING clause.

New in version 1.1.
rows¶ –
optional rows clause for the window. This is a tuple value which can contain integer values or None, and will render a ROWS BETWEEN PRECEDING / FOLLOWING clause.

New in version 1.1.

This function is also available from the func construct itself via the FunctionElement.over() method.

See also

func

within_group()

function sqlalchemy.sql.expression.text(text, bind=None, bindparams=None, typemap=None, autocommit=None)¶

Construct a new TextClause clause, representing a textual SQL string directly.

E.g.:

from sqlalchemy import text

t = text("SELECT * FROM users")
result = connection.execute(t)

The advantages text() provides over a plain string are backend-neutral support for bind parameters, per-statement execution options, as well as bind parameter and result-column typing behavior, allowing SQLAlchemy type constructs to play a role when executing a statement that is specified literally. The construct can also be provided with a .c collection of column elements, allowing it to be embedded in other SQL expression constructs as a subquery.

Bind parameters are specified by name, using the format :name. E.g.:

t = text("SELECT * FROM users WHERE id=:user_id")
result = connection.execute(t, user_id=12)

For SQL statements where a colon is required verbatim, as within an inline string, use a backslash to escape:

t = text("SELECT * FROM users WHERE name='\:username'")

The TextClause construct includes methods which can provide information about the bound parameters as well as the column values which would be returned from the textual statement, assuming it’s an executable SELECT type of statement. The TextClause.bindparams() method is used to provide bound parameter detail, and TextClause.columns() method allows specification of return columns including names and types:

t = text("SELECT * FROM users WHERE id=:user_id").\
        bindparams(user_id=7).\
        columns(id=Integer, name=String)

for id, name in connection.execute(t):
    print(id, name)

The text() construct is used in cases when a literal string SQL fragment is specified as part of a larger query, such as for the WHERE clause of a SELECT statement:

s = select([users.c.id, users.c.name]).where(text("id=:user_id"))
result = connection.execute(s, user_id=12)

text() is also used for the construction of a full, standalone statement using plain text. As such, SQLAlchemy refers to it as an Executable object, and it supports the Executable.execution_options() method. For example, a text() construct that should be subject to “autocommit” can be set explicitly so using the Connection.execution_options.autocommit option:

t = text("EXEC my_procedural_thing()").\
        execution_options(autocommit=True)

Note that SQLAlchemy’s usual “autocommit” behavior applies to text() constructs implicitly - that is, statements which begin with a phrase such as INSERT, UPDATE, DELETE, or a variety of other phrases specific to certain backends, will be eligible for autocommit if no transaction is in progress.

Parameters:

text¶ –
the text of the SQL statement to be created. Use :<param> to specify bind parameters; they will be compiled to their engine-specific format.

Warning

The text.text argument to text() can be passed as a Python string argument, which will be treated as trusted SQL text and rendered as given. DO NOT PASS UNTRUSTED INPUT TO THIS PARAMETER.
autocommit¶ –
whether or not to set the “autocommit” execution option for this TextClause object.

Deprecated since version 0.6: The text.autocommit parameter is deprecated and will be removed in a future release. Please use the Connection.execution_options.autocommit parameter in conjunction with the Executable.execution_options() method.
bind¶ – an optional connection or engine to be used for this text query.
bindparams¶ –
A list of bindparam() instances used to provide information about parameters embedded in the statement.

Deprecated since version 0.9: The text.bindparams parameter is deprecated and will be removed in a future release. Please refer to the TextClause.bindparams() method.

E.g.:
```
stmt = text("SELECT * FROM table WHERE id=:id",
          bindparams=[bindparam('id', value=5, type_=Integer)])
```
typemap¶ –
A dictionary mapping the names of columns represented in the columns clause of a SELECT statement to type objects.

Deprecated since version 0.9: The text.typemap parameter is deprecated and will be removed in a future release. Please refer to the TextClause.columns() method.

E.g.:
```
stmt = text("SELECT * FROM table",
              typemap={'id': Integer, 'name': String},
          )
```

See also

Using Textual SQL - in the Core tutorial

Using Textual SQL - in the ORM tutorial

function sqlalchemy.sql.expression.true()¶

Return a constant True_ construct.

E.g.:

>>> from sqlalchemy import true
>>> print(select([t.c.x]).where(true()))
SELECT x FROM t WHERE true

A backend which does not support true/false constants will render as an expression against 1 or 0:

>>> print(select([t.c.x]).where(true()))
SELECT x FROM t WHERE 1 = 1

The true() and false() constants also feature “short circuit” operation within an and_() or or_() conjunction:

>>> print(select([t.c.x]).where(or_(t.c.x > 5, true())))
SELECT x FROM t WHERE true

>>> print(select([t.c.x]).where(and_(t.c.x > 5, false())))
SELECT x FROM t WHERE false

Changed in version 0.9: true() and false() feature better integrated behavior within conjunctions and on dialects that don’t support true/false constants.

See also

false()

function sqlalchemy.sql.expression.tuple_(*clauses, **kw)¶

Return a Tuple.

Main usage is to produce a composite IN construct using ColumnOperators.in_()

from sqlalchemy import tuple_

tuple_(table.c.col1, table.c.col2).in_(
    [(1, 2), (5, 12), (10, 19)]
)

Changed in version 1.3.6: Added support for SQLite IN tuples.

Warning

The composite IN construct is not supported by all backends, and is currently known to work on PostgreSQL, MySQL, and SQLite. Unsupported backends will raise a subclass of DBAPIError when such an expression is invoked.

function sqlalchemy.sql.expression.type_coerce(expression, type_)¶

Associate a SQL expression with a particular type, without rendering CAST.

E.g.:

from sqlalchemy import type_coerce

stmt = select([type_coerce(log_table.date_string, StringDateTime())])

The above construct will produce a TypeCoerce object, which does not modify the rendering in any way on the SQL side, with the possible exception of a generated label if used in a columns clause context:

SELECT date_string AS anon_1 FROM log

When result rows are fetched, the StringDateTime type processor will be applied to result rows on behalf of the date_string column.

Note

the type_coerce() construct does not render any SQL syntax of its own, including that it does not imply parenthesization. Please use TypeCoerce.self_group() if explicit parenthesization is required.

In order to provide a named label for the expression, use ColumnElement.label():

stmt = select([
    type_coerce(log_table.date_string, StringDateTime()).label('date')
])

A type that features bound-value handling will also have that behavior take effect when literal values or bindparam() constructs are passed to type_coerce() as targets. For example, if a type implements the TypeEngine.bind_expression() method or TypeEngine.bind_processor() method or equivalent, these functions will take effect at statement compilation/execution time when a literal value is passed, as in:

# bound-value handling of MyStringType will be applied to the
# literal value "some string"
stmt = select([type_coerce("some string", MyStringType)])

When using type_coerce() with composed expressions, note that parenthesis are not applied. If type_coerce() is being used in an operator context where the parenthesis normally present from CAST are necessary, use the TypeCoerce.self_group() method:

>>> some_integer = column("someint", Integer)
>>> some_string = column("somestr", String)
>>> expr = type_coerce(some_integer + 5, String) + some_string
>>> print(expr)
someint + :someint_1 || somestr
>>> expr = type_coerce(some_integer + 5, String).self_group() + some_string
>>> print(expr)
(someint + :someint_1) || somestr

Parameters:

expression¶ – A SQL expression, such as a ColumnElement expression or a Python string which will be coerced into a bound literal value.
type_¶ – A TypeEngine class or instance indicating the type to which the expression is coerced.

See also

class sqlalchemy.sql.expression.BinaryExpression (sqlalchemy.sql.expression.ColumnElement)

function sqlalchemy.sql.expression.within_group(element, *order_by)¶

Produce a WithinGroup object against a function.

Used against so-called “ordered set aggregate” and “hypothetical set aggregate” functions, including percentile_cont, rank, dense_rank, etc.

within_group() is usually called using the FunctionElement.within_group() method, e.g.:

from sqlalchemy import within_group
stmt = select([
    department.c.id,
    func.percentile_cont(0.5).within_group(
        department.c.salary.desc()
    )
])

The above statement would produce SQL similar to SELECT department.id, percentile_cont(0.5) WITHIN GROUP (ORDER BY department.salary DESC).

Parameters:

element¶ – a FunctionElement construct, typically generated by func.
*order_by¶ – one or more column elements that will be used as the ORDER BY clause of the WITHIN GROUP construct.

New in version 1.1.

See also

func

over()

class sqlalchemy.sql.expression.BinaryExpression(left, right, operator, type_=None, negate=None, modifiers=None)¶

Represent an expression that is LEFT <operator> RIGHT.

A BinaryExpression is generated automatically whenever two column expressions are used in a Python binary expression:

>>> from sqlalchemy.sql import column
>>> column('a') + column('b')
<sqlalchemy.sql.expression.BinaryExpression object at 0x101029dd0>
>>> print(column('a') + column('b'))
a + b

Members

compare(), get_children(), self_group()

Class signature

method sqlalchemy.sql.expression.BinaryExpression.compare(other, **kw)¶: Compare this BinaryExpression against the given BinaryExpression.

method sqlalchemy.sql.expression.BinaryExpression.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

method sqlalchemy.sql.expression.BinaryExpression.self_group(against=None)¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

class sqlalchemy.sql.expression.BindParameter(key, value=symbol('NO_ARG'), type_=None, unique=False, required=symbol('NO_ARG'), quote=None, callable_=None, expanding=False, isoutparam=False, _compared_to_operator=None, _compared_to_type=None)¶

Represent a “bound expression”.

BindParameter is invoked explicitly using the bindparam() function, as in:

from sqlalchemy import bindparam

stmt = select([users_table]).\
            where(users_table.c.name == bindparam('username'))

Detailed discussion of how BindParameter is used is at bindparam().

See also

bindparam()

Members

__init__(), compare(), effective_value

Class signature

class sqlalchemy.sql.expression.BindParameter (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.BindParameter.__init__(key, value=symbol('NO_ARG'), type_=None, unique=False, required=symbol('NO_ARG'), quote=None, callable_=None, expanding=False, isoutparam=False, _compared_to_operator=None, _compared_to_type=None)¶

Construct a new BindParameter object.

This constructor is mirrored as a public API function; see sqlalchemy.sql.expression.bindparam() for a full usage and argument description.

method sqlalchemy.sql.expression.BindParameter.compare(other, **kw)¶: Compare this BindParameter to the given clause.

attribute sqlalchemy.sql.expression.BindParameter.effective_value¶

Return the value of this bound parameter, taking into account if the callable parameter was set.

The callable value will be evaluated and returned if present, else value.

class sqlalchemy.sql.expression.Case(whens, value=None, else_=None)¶

Represent a CASE expression.

Case is produced using the case() factory function, as in:

from sqlalchemy import case

stmt = select([users_table]).                    where(
                case(
                    [
                        (users_table.c.name == 'wendy', 'W'),
                        (users_table.c.name == 'jack', 'J')
                    ],
                    else_='E'
                )
            )

Details on Case usage is at case().

See also

case()

Members

__init__(), get_children()

Class signature

class sqlalchemy.sql.expression.Case (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Case.__init__(whens, value=None, else_=None)¶

Construct a new Case object.

This constructor is mirrored as a public API function; see sqlalchemy.sql.expression.case() for a full usage and argument description.

method sqlalchemy.sql.expression.Case.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

class sqlalchemy.sql.expression.Cast(expression, type_)¶

Represent a CAST expression.

Cast is produced using the cast() factory function, as in:

from sqlalchemy import cast, Numeric

stmt = select([
            cast(product_table.c.unit_price, Numeric(10, 4))
        ])

Details on Cast usage is at cast().

See also

__init__(), get_children()

type_coerce() - an alternative to CAST that coerces the type on the Python side only, which is often sufficient to generate the correct SQL and data coercion.

Members

Class signature

class sqlalchemy.sql.expression.Cast (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Cast.__init__(expression, type_)¶

Construct a new Cast object.

This constructor is mirrored as a public API function; see sqlalchemy.sql.expression.cast() for a full usage and argument description.

method sqlalchemy.sql.expression.Cast.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

class sqlalchemy.sql.expression.ClauseElement¶

Base class for elements of a programmatically constructed SQL expression.

Members

compare(), compile(), get_children(), params(), self_group(), unique_params()

Class signature

class sqlalchemy.sql.expression.ClauseElement (sqlalchemy.sql.visitors.Visitable)

method sqlalchemy.sql.expression.ClauseElement.compare(other, **kw)¶

Compare this ClauseElement to the given ClauseElement.

Subclasses should override the default behavior, which is a straight identity comparison.

**kw are arguments consumed by subclass compare() methods and may be used to modify the criteria for comparison (see ColumnElement).

method sqlalchemy.sql.expression.ClauseElement.compile(default, bind=None, dialect=None, **kw)¶

Compile this SQL expression.

The return value is a Compiled object. Calling str() or unicode() on the returned value will yield a string representation of the result. The Compiled object also can return a dictionary of bind parameter names and values using the params accessor.

Parameters:

bind¶ – An Engine or Connection from which a Compiled will be acquired. This argument takes precedence over this ClauseElement’s bound engine, if any.
column_keys¶ – Used for INSERT and UPDATE statements, a list of column names which should be present in the VALUES clause of the compiled statement. If None, all columns from the target table object are rendered.
dialect¶ – A Dialect instance from which a Compiled will be acquired. This argument takes precedence over the bind argument as well as this ClauseElement ‘s bound engine, if any.
inline¶ – Used for INSERT statements, for a dialect which does not support inline retrieval of newly generated primary key columns, will force the expression used to create the new primary key value to be rendered inline within the INSERT statement’s VALUES clause. This typically refers to Sequence execution but may also refer to any server-side default generation function associated with a primary key Column.
compile_kwargs¶ –
optional dictionary of additional parameters that will be passed through to the compiler within all “visit” methods. This allows any custom flag to be passed through to a custom compilation construct, for example. It is also used for the case of passing the literal_binds flag through:
```
from sqlalchemy.sql import table, column, select

t = table('t', column('x'))

s = select([t]).where(t.c.x == 5)

print(s.compile(compile_kwargs={"literal_binds": True}))
```
New in version 0.9.0.

method sqlalchemy.sql.expression.ClauseElement.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

method sqlalchemy.sql.expression.ClauseElement.params(*optionaldict, **kwargs)¶

Return a copy with bindparam() elements replaced.

Returns a copy of this ClauseElement with bindparam() elements replaced with values taken from the given dictionary:

>>> clause = column('x') + bindparam('foo')
>>> print(clause.compile().params)
{'foo':None}
>>> print(clause.params({'foo':7}).compile().params)
{'foo':7}

method sqlalchemy.sql.expression.ClauseElement.self_group(against=None)¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

method sqlalchemy.sql.expression.ClauseElement.unique_params(*optionaldict, **kwargs)¶

Return a copy with bindparam() elements replaced.

Same functionality as ClauseElement.params(), except adds unique=True to affected bind parameters so that multiple statements can be used.

class sqlalchemy.sql.expression.ClauseList(*clauses, **kwargs)¶

Describe a list of clauses, separated by an operator.

By default, is comma-separated, such as a column listing.

Members

compare(), get_children(), self_group()

Class signature

class sqlalchemy.sql.expression.ClauseList (sqlalchemy.sql.expression.ClauseElement)

method sqlalchemy.sql.expression.ClauseList.compare(other, **kw)¶: Compare this ClauseList to the given ClauseList, including a comparison of all the clause items.

method sqlalchemy.sql.expression.ClauseList.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

method sqlalchemy.sql.expression.ClauseList.self_group(against=None)¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

class sqlalchemy.sql.expression.ColumnClause(text, type_=None, is_literal=False, _selectable=None)¶

Represents a column expression from any textual string.

The ColumnClause, a lightweight analogue to the Column class, is typically invoked using the column() function, as in:

from sqlalchemy import column

id, name = column("id"), column("name")
stmt = select([id, name]).select_from("user")

The above statement would produce SQL like:

SELECT id, name FROM user

ColumnClause is the immediate superclass of the schema-specific Column object. While the Column class has all the same capabilities as ColumnClause, the ColumnClause class is usable by itself in those cases where behavioral requirements are limited to simple SQL expression generation. The object has none of the associations with schema-level metadata or with execution-time behavior that Column does, so in that sense is a “lightweight” version of Column.

Full details on ColumnClause usage is at column().

See also

column()

Column

Members

__init__()

Class signature

class sqlalchemy.sql.expression.ColumnClause (sqlalchemy.sql.expression.Immutable, sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.ColumnClause.__init__(text, type_=None, is_literal=False, _selectable=None)¶

Construct a new ColumnClause object.

This constructor is mirrored as a public API function; see sqlalchemy.sql.expression.column() for a full usage and argument description.

class sqlalchemy.sql.expression.ColumnCollection(*columns)¶

An ordered dictionary that stores a list of ColumnElement instances.

Overrides the __eq__() method to produce SQL clauses between sets of correlated columns.

Members

add(), as_immutable(), replace()

Class signature

class sqlalchemy.sql.expression.ColumnCollection (sqlalchemy.util.OrderedProperties)

method sqlalchemy.sql.expression.ColumnCollection.add(column)¶

Add a column to this collection.

The key attribute of the column will be used as the hash key for this dictionary.

method sqlalchemy.sql.expression.ColumnCollection.as_immutable()¶: Return an immutable proxy for this Properties.

method sqlalchemy.sql.expression.ColumnCollection.replace(column)¶

Add the given column to this collection, removing unaliased versions of this column as well as existing columns with the same key.

E.g.:

t = Table('sometable', metadata, Column('col1', Integer))
t.columns.replace(Column('col1', Integer, key='columnone'))

will remove the original ‘col1’ from the collection, and add the new column under the name ‘columnname’.

Used by schema.Column to override columns during table reflection.

class sqlalchemy.sql.expression.ColumnElement¶

Represent a column-oriented SQL expression suitable for usage in the “columns” clause, WHERE clause etc. of a statement.

While the most familiar kind of ColumnElement is the Column object, ColumnElement serves as the basis for any unit that may be present in a SQL expression, including the expressions themselves, SQL functions, bound parameters, literal expressions, keywords such as NULL, etc. ColumnElement is the ultimate base class for all such elements.

A wide variety of SQLAlchemy Core functions work at the SQL expression level, and are intended to accept instances of ColumnElement as arguments. These functions will typically document that they accept a “SQL expression” as an argument. What this means in terms of SQLAlchemy usually refers to an input which is either already in the form of a ColumnElement object, or a value which can be coerced into one. The coercion rules followed by most, but not all, SQLAlchemy Core functions with regards to SQL expressions are as follows:

a literal Python value, such as a string, integer or floating point value, boolean, datetime, Decimal object, or virtually any other Python object, will be coerced into a “literal bound value”. This generally means that a bindparam() will be produced featuring the given value embedded into the construct; the resulting BindParameter object is an instance of ColumnElement. The Python value will ultimately be sent to the DBAPI at execution time as a parameterized argument to the execute() or executemany() methods, after SQLAlchemy type-specific converters (e.g. those provided by any associated TypeEngine objects) are applied to the value.

any special object value, typically ORM-level constructs, which feature a method called __clause_element__(). The Core expression system looks for this method when an object of otherwise unknown type is passed to a function that is looking to coerce the argument into a ColumnElement expression. The __clause_element__() method, if present, should return a ColumnElement instance. The primary use of __clause_element__() within SQLAlchemy is that of class-bound attributes on ORM-mapped classes; a User class which contains a mapped attribute named .name will have a method User.name.__clause_element__() which when invoked returns the Column called name associated with the mapped table.

The Python None value is typically interpreted as NULL, which in SQLAlchemy Core produces an instance of null().

A ColumnElement provides the ability to generate new ColumnElement objects using Python expressions. This means that Python operators such as ==, != and < are overloaded to mimic SQL operations, and allow the instantiation of further ColumnElement instances which are composed from other, more fundamental ColumnElement objects. For example, two ColumnClause objects can be added together with the addition operator + to produce a BinaryExpression. Both ColumnClause and BinaryExpression are subclasses of ColumnElement:

>>> from sqlalchemy.sql import column
>>> column('a') + column('b')
<sqlalchemy.sql.expression.BinaryExpression object at 0x101029dd0>
>>> print(column('a') + column('b'))
a + b

See also

Column

column()

Class signature

class sqlalchemy.sql.expression.ColumnElement (sqlalchemy.sql.operators.ColumnOperators, sqlalchemy.sql.expression.ClauseElement)

method sqlalchemy.sql.expression.ColumnElement.__eq__(other)¶

inherited from the sqlalchemy.sql.operators.ColumnOperators.__eq__ method of ColumnOperators

Implement the == operator.

In a column context, produces the clause a = b. If the target is None, produces a IS NULL.

method sqlalchemy.sql.expression.ColumnElement.__le__(other)¶

inherited from the sqlalchemy.sql.operators.ColumnOperators.__le__ method of ColumnOperators

Implement the <= operator.

In a column context, produces the clause a <= b.

method sqlalchemy.sql.expression.ColumnElement.__lt__(other)¶

inherited from the sqlalchemy.sql.operators.ColumnOperators.__lt__ method of ColumnOperators

Implement the < operator.

In a column context, produces the clause a < b.

method sqlalchemy.sql.expression.ColumnElement.__ne__(other)¶

inherited from the sqlalchemy.sql.operators.ColumnOperators.__ne__ method of ColumnOperators

Implement the != operator.

In a column context, produces the clause a != b. If the target is None, produces a IS NOT NULL.

method sqlalchemy.sql.expression.ColumnElement.all_()¶

inherited from the ColumnOperators.all_() method of ColumnOperators

Produce a all_() clause against the parent object.

This operator is only appropriate against a scalar subquery object, or for some backends an column expression that is against the ARRAY type, e.g.:

# postgresql '5 = ALL (somearray)'
expr = 5 == mytable.c.somearray.all_()

# mysql '5 = ALL (SELECT value FROM table)'
expr = 5 == select([table.c.value]).as_scalar().all_()

See also

all_() - standalone version

any_() - ANY operator

New in version 1.1.

attribute sqlalchemy.sql.expression.ColumnElement.anon_label¶

Provides a constant ‘anonymous label’ for this ColumnElement.

This is a label() expression which will be named at compile time. The same label() is returned each time anon_label is called so that expressions can reference anon_label multiple times, producing the same label name at compile time.

The compiler uses this function automatically at compile time for expressions that are known to be ‘unnamed’ like binary expressions and function calls.

method sqlalchemy.sql.expression.ColumnElement.any_()¶

inherited from the ColumnOperators.any_() method of ColumnOperators

Produce a any_() clause against the parent object.

This operator is only appropriate against a scalar subquery object, or for some backends an column expression that is against the ARRAY type, e.g.:

# postgresql '5 = ANY (somearray)'
expr = 5 == mytable.c.somearray.any_()

# mysql '5 = ANY (SELECT value FROM table)'
expr = 5 == select([table.c.value]).as_scalar().any_()

See also

any_() - standalone version

all_() - ALL operator

New in version 1.1.

method sqlalchemy.sql.expression.ColumnElement.asc()¶: inherited from the ColumnOperators.asc() method of ColumnOperators

Produce a asc() clause against the parent object.

attribute sqlalchemy.sql.expression.ColumnElement.base_columns¶

method sqlalchemy.sql.expression.ColumnElement.between(cleft, cright, symmetric=False)¶: inherited from the ColumnOperators.between() method of ColumnOperators

Produce a between() clause against the parent object, given the lower and upper range.

attribute sqlalchemy.sql.expression.ColumnElement.bind = None¶

method sqlalchemy.sql.expression.ColumnElement.bool_op(opstring, precedence=0)¶

inherited from the Operators.bool_op() method of Operators

Return a custom boolean operator.

This method is shorthand for calling Operators.op() and passing the Operators.op.is_comparison flag with True.

New in version 1.2.0b3.

See also

method sqlalchemy.sql.expression.ColumnElement.cast(type_)¶

Produce a type cast, i.e. CAST(<expression> AS <type>).

This is a shortcut to the cast() function.

See also

type_coerce()

New in version 1.0.7.

method sqlalchemy.sql.expression.ColumnElement.collate(collation)¶: inherited from the ColumnOperators.collate() method of ColumnOperators

Produce a collate() clause against the parent object, given the collation string.

See also

collate()

attribute sqlalchemy.sql.expression.ColumnElement.comparator¶

method sqlalchemy.sql.expression.ColumnElement.compare(other, use_proxies=False, equivalents=None, **kw)¶

Compare this ColumnElement to another.

Special arguments understood:

Parameters:

use_proxies¶ – when True, consider two columns that share a common base column as equivalent (i.e. shares_lineage())
equivalents¶ – a dictionary of columns as keys mapped to sets of columns. If the given “other” column is present in this dictionary, if any of the columns in the corresponding set() pass the comparison test, the result is True. This is used to expand the comparison to other columns that may be known to be equivalent to this one via foreign key or other criterion.

method sqlalchemy.sql.expression.ColumnElement.compile(default, bind=None, dialect=None, **kw)¶

inherited from the ClauseElement.compile() method of ClauseElement

Compile this SQL expression.

The return value is a Compiled object. Calling str() or unicode() on the returned value will yield a string representation of the result. The Compiled object also can return a dictionary of bind parameter names and values using the params accessor.

Parameters:

bind¶ – An Engine or Connection from which a Compiled will be acquired. This argument takes precedence over this ClauseElement’s bound engine, if any.
column_keys¶ – Used for INSERT and UPDATE statements, a list of column names which should be present in the VALUES clause of the compiled statement. If None, all columns from the target table object are rendered.
dialect¶ – A Dialect instance from which a Compiled will be acquired. This argument takes precedence over the bind argument as well as this ClauseElement ‘s bound engine, if any.
inline¶ – Used for INSERT statements, for a dialect which does not support inline retrieval of newly generated primary key columns, will force the expression used to create the new primary key value to be rendered inline within the INSERT statement’s VALUES clause. This typically refers to Sequence execution but may also refer to any server-side default generation function associated with a primary key Column.
compile_kwargs¶ –
optional dictionary of additional parameters that will be passed through to the compiler within all “visit” methods. This allows any custom flag to be passed through to a custom compilation construct, for example. It is also used for the case of passing the literal_binds flag through:
```
from sqlalchemy.sql import table, column, select

t = table('t', column('x'))

s = select([t]).where(t.c.x == 5)

print(s.compile(compile_kwargs={"literal_binds": True}))
```
New in version 0.9.0.

method sqlalchemy.sql.expression.ColumnElement.concat(other)¶

inherited from the ColumnOperators.concat() method of ColumnOperators

Implement the ‘concat’ operator.

In a column context, produces the clause a || b, or uses the concat() operator on MySQL.

method sqlalchemy.sql.expression.ColumnElement.contains(other, **kwargs)¶

inherited from the ColumnOperators.contains() method of ColumnOperators

Implement the ‘contains’ operator.

Produces a LIKE expression that tests against a match for the middle of a string value:

column LIKE '%' || <other> || '%'

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.contains("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.contains.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.contains.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

other¶ – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.contains.autoescape flag is set to True.
autoescape¶ –
boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

An expression such as:
```
somecolumn.contains("foo%bar", autoescape=True)
```
Will render as:
```
somecolumn LIKE '%' || :param || '%' ESCAPE '/'
```
With the value of :param as "foo/%bar".

New in version 1.2.

Changed in version 1.2.0: The ColumnOperators.contains.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.contains.escape parameter.
escape¶ –
a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

An expression such as:
```
somecolumn.contains("foo/%bar", escape="^")
```
Will render as:
```
somecolumn LIKE '%' || :param || '%' ESCAPE '^'
```
The parameter may also be combined with ColumnOperators.contains.autoescape:
```
somecolumn.contains("foo%bar^bat", escape="^", autoescape=True)
```
Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

method sqlalchemy.sql.expression.ColumnElement.desc()¶: inherited from the ColumnOperators.desc() method of ColumnOperators

Produce a desc() clause against the parent object.

attribute sqlalchemy.sql.expression.ColumnElement.description = None¶

method sqlalchemy.sql.expression.ColumnElement.distinct()¶: inherited from the ColumnOperators.distinct() method of ColumnOperators

Produce a distinct() clause against the parent object.

method sqlalchemy.sql.expression.ColumnElement.endswith(other, **kwargs)¶

inherited from the ColumnOperators.endswith() method of ColumnOperators

Implement the ‘endswith’ operator.

Produces a LIKE expression that tests against a match for the end of a string value:

column LIKE '%' || <other>

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.endswith("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.endswith.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.endswith.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

other¶ – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.endswith.autoescape flag is set to True.
autoescape¶ –
boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

An expression such as:
```
somecolumn.endswith("foo%bar", autoescape=True)
```
Will render as:
```
somecolumn LIKE '%' || :param ESCAPE '/'
```
With the value of :param as "foo/%bar".

New in version 1.2.

Changed in version 1.2.0: The ColumnOperators.endswith.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.endswith.escape parameter.
escape¶ –
a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

An expression such as:
```
somecolumn.endswith("foo/%bar", escape="^")
```
Will render as:
```
somecolumn LIKE '%' || :param ESCAPE '^'
```
The parameter may also be combined with ColumnOperators.endswith.autoescape:
```
somecolumn.endswith("foo%bar^bat", escape="^", autoescape=True)
```
Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

attribute sqlalchemy.sql.expression.ColumnElement.expression¶

Return a column expression.

Part of the inspection interface; returns self.

attribute sqlalchemy.sql.expression.ColumnElement.foreign_keys = []¶

method sqlalchemy.sql.expression.ColumnElement.get_children(**kwargs)¶

inherited from the ClauseElement.get_children() method of ClauseElement

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

method sqlalchemy.sql.expression.ColumnElement.ilike(other, escape=None)¶

inherited from the ColumnOperators.ilike() method of ColumnOperators

Implement the ilike operator, e.g. case insensitive LIKE.

In a column context, produces an expression either of the form:

lower(a) LIKE lower(other)

Or on backends that support the ILIKE operator:

a ILIKE other

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.ilike("%foobar%"))

Parameters:

other¶ – expression to be compared
escape¶ –
optional escape character, renders the ESCAPE keyword, e.g.:
```
somecolumn.ilike("foo/%bar", escape="/")
```

See also

ColumnOperators.isnot()

method sqlalchemy.sql.expression.ColumnElement.in_(other)¶

inherited from the ColumnOperators.in_() method of ColumnOperators

Implement the in operator.

In a column context, produces the clause column IN <other>.

The given parameter other may be:

A list of literal values, e.g.:
```
stmt.where(column.in_([1, 2, 3]))
```
In this calling form, the list of items is converted to a set of bound parameters the same length as the list given:
```
WHERE COL IN (?, ?, ?)
```

A list of tuples may be provided if the comparison is against a tuple_() containing multiple expressions:

from sqlalchemy import tuple_
stmt.where(tuple_(col1, col2).in_([(1, 10), (2, 20), (3, 30)]))

An empty list, e.g.:
```
stmt.where(column.in_([]))
```
In this calling form, the expression renders a “false” expression, e.g.:
```
WHERE 1 != 1
```
This “false” expression has historically had different behaviors in older SQLAlchemy versions, see create_engine.empty_in_strategy for behavioral options.

Changed in version 1.2: simplified the behavior of “empty in” expressions
A bound parameter, e.g. bindparam(), may be used if it includes the bindparam.expanding flag:
```
stmt.where(column.in_(bindparam('value', expanding=True)))
```
In this calling form, the expression renders a special non-SQL placeholder expression that looks like:
```
WHERE COL IN ([EXPANDING_value])
```
This placeholder expression is intercepted at statement execution time to be converted into the variable number of bound parameter form illustrated earlier. If the statement were executed as:
```
connection.execute(stmt, {"value": [1, 2, 3]})
```
The database would be passed a bound parameter for each value:
```
WHERE COL IN (?, ?, ?)
```
New in version 1.2: added “expanding” bound parameters

If an empty list is passed, a special “empty list” expression, which is specific to the database in use, is rendered. On SQLite this would be:
```
WHERE COL IN (SELECT 1 FROM (SELECT 1) WHERE 1!=1)
```
New in version 1.3: “expanding” bound parameters now support empty lists

a select() construct, which is usually a correlated scalar select:

stmt.where(
    column.in_(
        select([othertable.c.y]).
        where(table.c.x == othertable.c.x)
    )
)

In this calling form, ColumnOperators.in_() renders as given:

WHERE COL IN (SELECT othertable.y
FROM othertable WHERE othertable.x = table.x)

Parameters:: other¶ – a list of literals, a select() construct, or a bindparam() construct that includes the bindparam.expanding flag set to True.

method sqlalchemy.sql.expression.ColumnElement.is_(other)¶

inherited from the ColumnOperators.is_() method of ColumnOperators

Implement the IS operator.

Normally, IS is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS may be desirable if comparing to boolean values on certain platforms.

See also

attribute sqlalchemy.sql.expression.ColumnElement.is_clause_element = True¶

method sqlalchemy.sql.expression.ColumnElement.is_distinct_from(other)¶

inherited from the ColumnOperators.is_distinct_from() method of ColumnOperators

Implement the IS DISTINCT FROM operator.

Renders “a IS DISTINCT FROM b” on most platforms; on some such as SQLite may render “a IS NOT b”.

New in version 1.1.

attribute sqlalchemy.sql.expression.ColumnElement.is_selectable = False¶

method sqlalchemy.sql.expression.ColumnElement.isnot(other)¶

inherited from the ColumnOperators.isnot() method of ColumnOperators

Implement the IS NOT operator.

Normally, IS NOT is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS NOT may be desirable if comparing to boolean values on certain platforms.

See also

ColumnOperators.is_()

method sqlalchemy.sql.expression.ColumnElement.isnot_distinct_from(other)¶

inherited from the ColumnOperators.isnot_distinct_from() method of ColumnOperators

Implement the IS NOT DISTINCT FROM operator.

Renders “a IS NOT DISTINCT FROM b” on most platforms; on some such as SQLite may render “a IS b”.

New in version 1.1.

attribute sqlalchemy.sql.expression.ColumnElement.key = None¶

The ‘key’ that in some circumstances refers to this object in a Python namespace.

This typically refers to the “key” of the column as present in the .c collection of a selectable, e.g. sometable.c["somekey"] would return a Column with a .key of “somekey”.

method sqlalchemy.sql.expression.ColumnElement.label(name)¶

Produce a column label, i.e. <columnname> AS <name>.

This is a shortcut to the label() function.

If ‘name’ is None, an anonymous label name will be generated.

method sqlalchemy.sql.expression.ColumnElement.like(other, escape=None)¶

inherited from the ColumnOperators.like() method of ColumnOperators

Implement the like operator.

In a column context, produces the expression:

a LIKE other

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.like("%foobar%"))

Parameters:

other¶ – expression to be compared
escape¶ –
optional escape character, renders the ESCAPE keyword, e.g.:
```
somecolumn.like("foo/%bar", escape="/")
```

See also

method sqlalchemy.sql.expression.ColumnElement.match(other, **kwargs)¶

inherited from the ColumnOperators.match() method of ColumnOperators

Implements a database-specific ‘match’ operator.

ColumnOperators.match() attempts to resolve to a MATCH-like function or operator provided by the backend. Examples include:

PostgreSQL - renders x @@ to_tsquery(y)
MySQL - renders MATCH (x) AGAINST (y IN BOOLEAN MODE)
Oracle - renders CONTAINS(x, y)
other backends may provide special implementations.
Backends without any special implementation will emit the operator as “MATCH”. This is compatible with SQLite, for example.

method sqlalchemy.sql.expression.ColumnElement.notilike(other, escape=None)¶

inherited from the ColumnOperators.notilike() method of ColumnOperators

implement the NOT ILIKE operator.

This is equivalent to using negation with ColumnOperators.ilike(), i.e. ~x.ilike(y).

See also

method sqlalchemy.sql.expression.ColumnElement.notin_(other)¶

inherited from the ColumnOperators.notin_() method of ColumnOperators

implement the NOT IN operator.

This is equivalent to using negation with ColumnOperators.in_(), i.e. ~x.in_(y).

In the case that other is an empty sequence, the compiler produces an “empty not in” expression. This defaults to the expression “1 = 1” to produce true in all cases. The create_engine.empty_in_strategy may be used to alter this behavior.

Changed in version 1.2: The ColumnOperators.in_() and ColumnOperators.notin_() operators now produce a “static” expression for an empty IN sequence by default.

See also

ColumnOperators.in_()

method sqlalchemy.sql.expression.ColumnElement.notlike(other, escape=None)¶

inherited from the ColumnOperators.notlike() method of ColumnOperators

implement the NOT LIKE operator.

This is equivalent to using negation with ColumnOperators.like(), i.e. ~x.like(y).

See also

method sqlalchemy.sql.expression.ColumnElement.nullsfirst()¶: inherited from the ColumnOperators.nullsfirst() method of ColumnOperators

Produce a nullsfirst() clause against the parent object.

method sqlalchemy.sql.expression.ColumnElement.nullslast()¶: inherited from the ColumnOperators.nullslast() method of ColumnOperators

Produce a nullslast() clause against the parent object.

method sqlalchemy.sql.expression.ColumnElement.op(opstring, precedence=0, is_comparison=False, return_type=None)¶

inherited from the Operators.op() method of Operators

Produce a generic operator function.

e.g.:

somecolumn.op("*")(5)

produces:

somecolumn * 5

This function can also be used to make bitwise operators explicit. For example:

somecolumn.op('&')(0xff)

is a bitwise AND of the value in somecolumn.

Parameters:

operator¶ – a string which will be output as the infix operator between this element and the expression passed to the generated function.
precedence¶ – precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of 0 is lower than all operators except for the comma (,) and AS operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators.
is_comparison¶ –
if True, the operator will be considered as a “comparison” operator, that is which evaluates to a boolean true/false value, like ==, >, etc. This flag should be set so that ORM relationships can establish that the operator is a comparison operator when used in a custom join condition.

New in version 0.9.2: - added the Operators.op.is_comparison flag.
return_type¶ –
a TypeEngine class or object that will force the return type of an expression produced by this operator to be of that type. By default, operators that specify Operators.op.is_comparison will resolve to Boolean, and those that do not will be of the same type as the left-hand operand.

New in version 1.2.0b3: - added the Operators.op.return_type argument.

See also

Using custom operators in join conditions

method sqlalchemy.sql.expression.ColumnElement.operate(op, *other, **kwargs)¶

Operate on an argument.

This is the lowest level of operation, raises NotImplementedError by default.

Overriding this on a subclass can allow common behavior to be applied to all operations. For example, overriding ColumnOperators to apply func.lower() to the left and right side:

class MyComparator(ColumnOperators):
    def operate(self, op, other):
        return op(func.lower(self), func.lower(other))

Parameters:

op¶ – Operator callable.
*other¶ – the ‘other’ side of the operation. Will be a single scalar for most operations.
**kwargs¶ – modifiers. These may be passed by special operators such as ColumnOperators.contains().

method sqlalchemy.sql.expression.ColumnElement.params(*optionaldict, **kwargs)¶

inherited from the ClauseElement.params() method of ClauseElement

Return a copy with bindparam() elements replaced.

Returns a copy of this ClauseElement with bindparam() elements replaced with values taken from the given dictionary:

>>> clause = column('x') + bindparam('foo')
>>> print(clause.compile().params)
{'foo':None}
>>> print(clause.params({'foo':7}).compile().params)
{'foo':7}

attribute sqlalchemy.sql.expression.ColumnElement.primary_key = False¶

attribute sqlalchemy.sql.expression.ColumnElement.proxy_set¶

method sqlalchemy.sql.expression.ColumnElement.reverse_operate(op, other, **kwargs)¶

Reverse operate on an argument.

Usage is the same as operate().

method sqlalchemy.sql.expression.ColumnElement.self_group(against=None)¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

method sqlalchemy.sql.expression.ColumnElement.shares_lineage(othercolumn)¶: Return True if the given ColumnElement has a common ancestor to this ColumnElement.

method sqlalchemy.sql.expression.ColumnElement.startswith(other, **kwargs)¶

inherited from the ColumnOperators.startswith() method of ColumnOperators

Implement the startswith operator.

Produces a LIKE expression that tests against a match for the start of a string value:

column LIKE <other> || '%'

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.startswith("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.startswith.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.startswith.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

other¶ – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.startswith.autoescape flag is set to True.
autoescape¶ –
boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

An expression such as:
```
somecolumn.startswith("foo%bar", autoescape=True)
```
Will render as:
```
somecolumn LIKE :param || '%' ESCAPE '/'
```
With the value of :param as "foo/%bar".

New in version 1.2.

Changed in version 1.2.0: The ColumnOperators.startswith.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.startswith.escape parameter.
escape¶ –
a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

An expression such as:
```
somecolumn.startswith("foo/%bar", escape="^")
```
Will render as:
```
somecolumn LIKE :param || '%' ESCAPE '^'
```
The parameter may also be combined with ColumnOperators.startswith.autoescape:
```
somecolumn.startswith("foo%bar^bat", escape="^", autoescape=True)
```
Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

attribute sqlalchemy.sql.expression.ColumnElement.supports_execution = False¶

attribute sqlalchemy.sql.expression.ColumnElement.timetuple = None¶: inherited from the ColumnOperators.timetuple attribute of ColumnOperators

Hack, allows datetime objects to be compared on the LHS.

attribute sqlalchemy.sql.expression.ColumnElement.type¶

method sqlalchemy.sql.expression.ColumnElement.unique_params(*optionaldict, **kwargs)¶

inherited from the ClauseElement.unique_params() method of ClauseElement

Return a copy with bindparam() elements replaced.

Same functionality as ClauseElement.params(), except adds unique=True to affected bind parameters so that multiple statements can be used.

class sqlalchemy.sql.operators.ColumnOperators¶

Defines boolean, comparison, and other operators for ColumnElement expressions.

By default, all methods call down to operate() or reverse_operate(), passing in the appropriate operator function from the Python builtin operator module or a SQLAlchemy-specific operator function from sqlalchemy.expression.operators. For example the __eq__ function:

def __eq__(self, other):
    return self.operate(operators.eq, other)

Where operators.eq is essentially:

def eq(a, b):
    return a == b

The core column expression unit ColumnElement overrides Operators.operate() and others to return further ColumnElement constructs, so that the == operation above is replaced by a clause construct.

See also

TypeEngine.comparator_factory

ColumnOperators

PropComparator

Class signature

class sqlalchemy.sql.operators.ColumnOperators (sqlalchemy.sql.operators.Operators)

method sqlalchemy.sql.operators.ColumnOperators.__add__(other)¶

Implement the + operator.

In a column context, produces the clause a + b if the parent object has non-string affinity. If the parent object has a string affinity, produces the concatenation operator, a || b - see ColumnOperators.concat().

method sqlalchemy.sql.operators.ColumnOperators.__and__(other)¶

inherited from the sqlalchemy.sql.operators.Operators.__and__ method of Operators

Implement the & operator.

When used with SQL expressions, results in an AND operation, equivalent to and_(), that is:

a & b

is equivalent to:

from sqlalchemy import and_
and_(a, b)

Care should be taken when using & regarding operator precedence; the & operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

(a == 2) & (b == 4)

method sqlalchemy.sql.operators.ColumnOperators.__div__(other)¶

Implement the / operator.

In a column context, produces the clause a / b.

method sqlalchemy.sql.operators.ColumnOperators.__eq__(other)¶

Implement the == operator.

In a column context, produces the clause a = b. If the target is None, produces a IS NULL.

method sqlalchemy.sql.operators.ColumnOperators.__ge__(other)¶

Implement the >= operator.

In a column context, produces the clause a >= b.

method sqlalchemy.sql.operators.ColumnOperators.__getitem__(index)¶

Implement the [] operator.

This can be used by some database-specific types such as PostgreSQL ARRAY and HSTORE.

method sqlalchemy.sql.operators.ColumnOperators.__gt__(other)¶

Implement the > operator.

In a column context, produces the clause a > b.

method sqlalchemy.sql.operators.ColumnOperators.__hash__()¶: Return hash(self).

method sqlalchemy.sql.operators.ColumnOperators.__invert__()¶

inherited from the sqlalchemy.sql.operators.Operators.__invert__ method of Operators

Implement the ~ operator.

When used with SQL expressions, results in a NOT operation, equivalent to not_(), that is:

~a

is equivalent to:

from sqlalchemy import not_
not_(a)

method sqlalchemy.sql.operators.ColumnOperators.__le__(other)¶

Implement the <= operator.

In a column context, produces the clause a <= b.

method sqlalchemy.sql.operators.ColumnOperators.__lshift__(other)¶

implement the << operator.

Not used by SQLAlchemy core, this is provided for custom operator systems which want to use << as an extension point.

method sqlalchemy.sql.operators.ColumnOperators.__lt__(other)¶

Implement the < operator.

In a column context, produces the clause a < b.

method sqlalchemy.sql.operators.ColumnOperators.__mod__(other)¶

Implement the % operator.

In a column context, produces the clause a % b.

method sqlalchemy.sql.operators.ColumnOperators.__mul__(other)¶

Implement the * operator.

In a column context, produces the clause a * b.

method sqlalchemy.sql.operators.ColumnOperators.__ne__(other)¶

Implement the != operator.

In a column context, produces the clause a != b. If the target is None, produces a IS NOT NULL.

method sqlalchemy.sql.operators.ColumnOperators.__neg__()¶

Implement the - operator.

In a column context, produces the clause -a.

method sqlalchemy.sql.operators.ColumnOperators.__or__(other)¶

inherited from the sqlalchemy.sql.operators.Operators.__or__ method of Operators

Implement the | operator.

When used with SQL expressions, results in an OR operation, equivalent to or_(), that is:

a | b

is equivalent to:

from sqlalchemy import or_
or_(a, b)

Care should be taken when using | regarding operator precedence; the | operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

(a == 2) | (b == 4)

method sqlalchemy.sql.operators.ColumnOperators.__radd__(other)¶

Implement the + operator in reverse.

See ColumnOperators.__add__().

method sqlalchemy.sql.operators.ColumnOperators.__rdiv__(other)¶

Implement the / operator in reverse.

See ColumnOperators.__div__().

method sqlalchemy.sql.operators.ColumnOperators.__rmod__(other)¶

Implement the % operator in reverse.

See ColumnOperators.__mod__().

method sqlalchemy.sql.operators.ColumnOperators.__rmul__(other)¶

Implement the * operator in reverse.

See ColumnOperators.__mul__().

method sqlalchemy.sql.operators.ColumnOperators.__rshift__(other)¶

implement the >> operator.

Not used by SQLAlchemy core, this is provided for custom operator systems which want to use >> as an extension point.

method sqlalchemy.sql.operators.ColumnOperators.__rsub__(other)¶

Implement the - operator in reverse.

See ColumnOperators.__sub__().

method sqlalchemy.sql.operators.ColumnOperators.__rtruediv__(other)¶

Implement the // operator in reverse.

See ColumnOperators.__truediv__().

method sqlalchemy.sql.operators.ColumnOperators.__sub__(other)¶

Implement the - operator.

In a column context, produces the clause a - b.

method sqlalchemy.sql.operators.ColumnOperators.__truediv__(other)¶

Implement the // operator.

In a column context, produces the clause a / b.

method sqlalchemy.sql.operators.ColumnOperators.all_()¶

Produce a all_() clause against the parent object.

This operator is only appropriate against a scalar subquery object, or for some backends an column expression that is against the ARRAY type, e.g.:

# postgresql '5 = ALL (somearray)'
expr = 5 == mytable.c.somearray.all_()

# mysql '5 = ALL (SELECT value FROM table)'
expr = 5 == select([table.c.value]).as_scalar().all_()

See also

all_() - standalone version

any_() - ANY operator

New in version 1.1.

method sqlalchemy.sql.operators.ColumnOperators.any_()¶

Produce a any_() clause against the parent object.

This operator is only appropriate against a scalar subquery object, or for some backends an column expression that is against the ARRAY type, e.g.:

# postgresql '5 = ANY (somearray)'
expr = 5 == mytable.c.somearray.any_()

# mysql '5 = ANY (SELECT value FROM table)'
expr = 5 == select([table.c.value]).as_scalar().any_()

See also

any_() - standalone version

all_() - ALL operator

New in version 1.1.

method sqlalchemy.sql.operators.ColumnOperators.asc()¶: Produce a asc() clause against the parent object.

method sqlalchemy.sql.operators.ColumnOperators.between(cleft, cright, symmetric=False)¶: Produce a between() clause against the parent object, given the lower and upper range.

method sqlalchemy.sql.operators.ColumnOperators.bool_op(opstring, precedence=0)¶

inherited from the Operators.bool_op() method of Operators

Return a custom boolean operator.

This method is shorthand for calling Operators.op() and passing the Operators.op.is_comparison flag with True.

New in version 1.2.0b3.

See also

method sqlalchemy.sql.operators.ColumnOperators.collate(collation)¶: Produce a collate() clause against the parent object, given the collation string.

See also

collate()

method sqlalchemy.sql.operators.ColumnOperators.concat(other)¶

Implement the ‘concat’ operator.

In a column context, produces the clause a || b, or uses the concat() operator on MySQL.

method sqlalchemy.sql.operators.ColumnOperators.contains(other, **kwargs)¶

Implement the ‘contains’ operator.

Produces a LIKE expression that tests against a match for the middle of a string value:

column LIKE '%' || <other> || '%'

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.contains("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.contains.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.contains.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

other¶ – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.contains.autoescape flag is set to True.
autoescape¶ –
boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

An expression such as:
```
somecolumn.contains("foo%bar", autoescape=True)
```
Will render as:
```
somecolumn LIKE '%' || :param || '%' ESCAPE '/'
```
With the value of :param as "foo/%bar".

New in version 1.2.

Changed in version 1.2.0: The ColumnOperators.contains.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.contains.escape parameter.
escape¶ –
a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

An expression such as:
```
somecolumn.contains("foo/%bar", escape="^")
```
Will render as:
```
somecolumn LIKE '%' || :param || '%' ESCAPE '^'
```
The parameter may also be combined with ColumnOperators.contains.autoescape:
```
somecolumn.contains("foo%bar^bat", escape="^", autoescape=True)
```
Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

method sqlalchemy.sql.operators.ColumnOperators.desc()¶: Produce a desc() clause against the parent object.

method sqlalchemy.sql.operators.ColumnOperators.distinct()¶: Produce a distinct() clause against the parent object.

method sqlalchemy.sql.operators.ColumnOperators.endswith(other, **kwargs)¶

Implement the ‘endswith’ operator.

Produces a LIKE expression that tests against a match for the end of a string value:

column LIKE '%' || <other>

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.endswith("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.endswith.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.endswith.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

other¶ – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.endswith.autoescape flag is set to True.
autoescape¶ –
boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

An expression such as:
```
somecolumn.endswith("foo%bar", autoescape=True)
```
Will render as:
```
somecolumn LIKE '%' || :param ESCAPE '/'
```
With the value of :param as "foo/%bar".

New in version 1.2.

Changed in version 1.2.0: The ColumnOperators.endswith.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.endswith.escape parameter.
escape¶ –
a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

An expression such as:
```
somecolumn.endswith("foo/%bar", escape="^")
```
Will render as:
```
somecolumn LIKE '%' || :param ESCAPE '^'
```
The parameter may also be combined with ColumnOperators.endswith.autoescape:
```
somecolumn.endswith("foo%bar^bat", escape="^", autoescape=True)
```
Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

method sqlalchemy.sql.operators.ColumnOperators.ilike(other, escape=None)¶

Implement the ilike operator, e.g. case insensitive LIKE.

In a column context, produces an expression either of the form:

lower(a) LIKE lower(other)

Or on backends that support the ILIKE operator:

a ILIKE other

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.ilike("%foobar%"))

Parameters:

other¶ – expression to be compared
escape¶ –
optional escape character, renders the ESCAPE keyword, e.g.:
```
somecolumn.ilike("foo/%bar", escape="/")
```

See also

ColumnOperators.isnot()

method sqlalchemy.sql.operators.ColumnOperators.in_(other)¶

Implement the in operator.

In a column context, produces the clause column IN <other>.

The given parameter other may be:

A list of literal values, e.g.:
```
stmt.where(column.in_([1, 2, 3]))
```
In this calling form, the list of items is converted to a set of bound parameters the same length as the list given:
```
WHERE COL IN (?, ?, ?)
```

A list of tuples may be provided if the comparison is against a tuple_() containing multiple expressions:

from sqlalchemy import tuple_
stmt.where(tuple_(col1, col2).in_([(1, 10), (2, 20), (3, 30)]))

An empty list, e.g.:
```
stmt.where(column.in_([]))
```
In this calling form, the expression renders a “false” expression, e.g.:
```
WHERE 1 != 1
```
This “false” expression has historically had different behaviors in older SQLAlchemy versions, see create_engine.empty_in_strategy for behavioral options.

Changed in version 1.2: simplified the behavior of “empty in” expressions
A bound parameter, e.g. bindparam(), may be used if it includes the bindparam.expanding flag:
```
stmt.where(column.in_(bindparam('value', expanding=True)))
```
In this calling form, the expression renders a special non-SQL placeholder expression that looks like:
```
WHERE COL IN ([EXPANDING_value])
```
This placeholder expression is intercepted at statement execution time to be converted into the variable number of bound parameter form illustrated earlier. If the statement were executed as:
```
connection.execute(stmt, {"value": [1, 2, 3]})
```
The database would be passed a bound parameter for each value:
```
WHERE COL IN (?, ?, ?)
```
New in version 1.2: added “expanding” bound parameters

If an empty list is passed, a special “empty list” expression, which is specific to the database in use, is rendered. On SQLite this would be:
```
WHERE COL IN (SELECT 1 FROM (SELECT 1) WHERE 1!=1)
```
New in version 1.3: “expanding” bound parameters now support empty lists

a select() construct, which is usually a correlated scalar select:

stmt.where(
    column.in_(
        select([othertable.c.y]).
        where(table.c.x == othertable.c.x)
    )
)

In this calling form, ColumnOperators.in_() renders as given:

WHERE COL IN (SELECT othertable.y
FROM othertable WHERE othertable.x = table.x)

Parameters:: other¶ – a list of literals, a select() construct, or a bindparam() construct that includes the bindparam.expanding flag set to True.

method sqlalchemy.sql.operators.ColumnOperators.is_(other)¶

Implement the IS operator.

Normally, IS is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS may be desirable if comparing to boolean values on certain platforms.

See also

method sqlalchemy.sql.operators.ColumnOperators.is_distinct_from(other)¶

Implement the IS DISTINCT FROM operator.

Renders “a IS DISTINCT FROM b” on most platforms; on some such as SQLite may render “a IS NOT b”.

New in version 1.1.

method sqlalchemy.sql.operators.ColumnOperators.isnot(other)¶

Implement the IS NOT operator.

Normally, IS NOT is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS NOT may be desirable if comparing to boolean values on certain platforms.

See also

ColumnOperators.is_()

method sqlalchemy.sql.operators.ColumnOperators.isnot_distinct_from(other)¶

Implement the IS NOT DISTINCT FROM operator.

Renders “a IS NOT DISTINCT FROM b” on most platforms; on some such as SQLite may render “a IS b”.

New in version 1.1.

method sqlalchemy.sql.operators.ColumnOperators.like(other, escape=None)¶

Implement the like operator.

In a column context, produces the expression:

a LIKE other

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.like("%foobar%"))

Parameters:

other¶ – expression to be compared
escape¶ –
optional escape character, renders the ESCAPE keyword, e.g.:
```
somecolumn.like("foo/%bar", escape="/")
```

See also

method sqlalchemy.sql.operators.ColumnOperators.match(other, **kwargs)¶

Implements a database-specific ‘match’ operator.

ColumnOperators.match() attempts to resolve to a MATCH-like function or operator provided by the backend. Examples include:

PostgreSQL - renders x @@ to_tsquery(y)
MySQL - renders MATCH (x) AGAINST (y IN BOOLEAN MODE)
Oracle - renders CONTAINS(x, y)
other backends may provide special implementations.
Backends without any special implementation will emit the operator as “MATCH”. This is compatible with SQLite, for example.

method sqlalchemy.sql.operators.ColumnOperators.notilike(other, escape=None)¶

implement the NOT ILIKE operator.

This is equivalent to using negation with ColumnOperators.ilike(), i.e. ~x.ilike(y).

See also

method sqlalchemy.sql.operators.ColumnOperators.notin_(other)¶

implement the NOT IN operator.

This is equivalent to using negation with ColumnOperators.in_(), i.e. ~x.in_(y).

In the case that other is an empty sequence, the compiler produces an “empty not in” expression. This defaults to the expression “1 = 1” to produce true in all cases. The create_engine.empty_in_strategy may be used to alter this behavior.

Changed in version 1.2: The ColumnOperators.in_() and ColumnOperators.notin_() operators now produce a “static” expression for an empty IN sequence by default.

See also

ColumnOperators.in_()

method sqlalchemy.sql.operators.ColumnOperators.notlike(other, escape=None)¶

implement the NOT LIKE operator.

This is equivalent to using negation with ColumnOperators.like(), i.e. ~x.like(y).

See also

method sqlalchemy.sql.operators.ColumnOperators.nullsfirst()¶: Produce a nullsfirst() clause against the parent object.

method sqlalchemy.sql.operators.ColumnOperators.nullslast()¶: Produce a nullslast() clause against the parent object.

method sqlalchemy.sql.operators.ColumnOperators.op(opstring, precedence=0, is_comparison=False, return_type=None)¶

inherited from the Operators.op() method of Operators

Produce a generic operator function.

e.g.:

somecolumn.op("*")(5)

produces:

somecolumn * 5

This function can also be used to make bitwise operators explicit. For example:

somecolumn.op('&')(0xff)

is a bitwise AND of the value in somecolumn.

Parameters:

operator¶ – a string which will be output as the infix operator between this element and the expression passed to the generated function.
precedence¶ – precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of 0 is lower than all operators except for the comma (,) and AS operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators.
is_comparison¶ –
if True, the operator will be considered as a “comparison” operator, that is which evaluates to a boolean true/false value, like ==, >, etc. This flag should be set so that ORM relationships can establish that the operator is a comparison operator when used in a custom join condition.

New in version 0.9.2: - added the Operators.op.is_comparison flag.
return_type¶ –
a TypeEngine class or object that will force the return type of an expression produced by this operator to be of that type. By default, operators that specify Operators.op.is_comparison will resolve to Boolean, and those that do not will be of the same type as the left-hand operand.

New in version 1.2.0b3: - added the Operators.op.return_type argument.

See also

Using custom operators in join conditions

method sqlalchemy.sql.operators.ColumnOperators.operate(op, *other, **kwargs)¶

inherited from the Operators.operate() method of Operators

Operate on an argument.

This is the lowest level of operation, raises NotImplementedError by default.

Overriding this on a subclass can allow common behavior to be applied to all operations. For example, overriding ColumnOperators to apply func.lower() to the left and right side:

class MyComparator(ColumnOperators):
    def operate(self, op, other):
        return op(func.lower(self), func.lower(other))

Parameters:

op¶ – Operator callable.
*other¶ – the ‘other’ side of the operation. Will be a single scalar for most operations.
**kwargs¶ – modifiers. These may be passed by special operators such as ColumnOperators.contains().

method sqlalchemy.sql.operators.ColumnOperators.reverse_operate(op, other, **kwargs)¶

inherited from the Operators.reverse_operate() method of Operators

Reverse operate on an argument.

Usage is the same as operate().

method sqlalchemy.sql.operators.ColumnOperators.startswith(other, **kwargs)¶

Implement the startswith operator.

Produces a LIKE expression that tests against a match for the start of a string value:

column LIKE <other> || '%'

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.startswith("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.startswith.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.startswith.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

other¶ – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.startswith.autoescape flag is set to True.
autoescape¶ –
boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

An expression such as:
```
somecolumn.startswith("foo%bar", autoescape=True)
```
Will render as:
```
somecolumn LIKE :param || '%' ESCAPE '/'
```
With the value of :param as "foo/%bar".

New in version 1.2.

Changed in version 1.2.0: The ColumnOperators.startswith.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.startswith.escape parameter.
escape¶ –
a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

An expression such as:
```
somecolumn.startswith("foo/%bar", escape="^")
```
Will render as:
```
somecolumn LIKE :param || '%' ESCAPE '^'
```
The parameter may also be combined with ColumnOperators.startswith.autoescape:
```
somecolumn.startswith("foo%bar^bat", escape="^", autoescape=True)
```
Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

DefaultDialect.construct_arguments

attribute sqlalchemy.sql.operators.ColumnOperators.timetuple = None¶: Hack, allows datetime objects to be compared on the LHS.

class sqlalchemy.sql.base.DialectKWArgs¶

Establish the ability for a class to have dialect-specific arguments with defaults and constructor validation.

The DialectKWArgs interacts with the DefaultDialect.construct_arguments present on a dialect.

Members

argument_for(), dialect_kwargs, dialect_options, kwargs

See also

classmethod sqlalchemy.sql.base.DialectKWArgs.argument_for(dialect_name, argument_name, default)¶

Add a new kind of dialect-specific keyword argument for this class.

E.g.:

Index.argument_for("mydialect", "length", None)

some_index = Index('a', 'b', mydialect_length=5)

The DialectKWArgs.argument_for() method is a per-argument way adding extra arguments to the DefaultDialect.construct_arguments dictionary. This dictionary provides a list of argument names accepted by various schema-level constructs on behalf of a dialect.

New dialects should typically specify this dictionary all at once as a data member of the dialect class. The use case for ad-hoc addition of argument names is typically for end-user code that is also using a custom compilation scheme which consumes the additional arguments.

Parameters:

dialect_name¶ – name of a dialect. The dialect must be locatable, else a NoSuchModuleError is raised. The dialect must also include an existing DefaultDialect.construct_arguments collection, indicating that it participates in the keyword-argument validation and default system, else ArgumentError is raised. If the dialect does not include this collection, then any keyword argument can be specified on behalf of this dialect already. All dialects packaged within SQLAlchemy include this collection, however for third party dialects, support may vary.
argument_name¶ – name of the parameter.
default¶ – default value of the parameter.

New in version 0.9.4.

attribute sqlalchemy.sql.base.DialectKWArgs.dialect_kwargs¶

A collection of keyword arguments specified as dialect-specific options to this construct.

The arguments are present here in their original <dialect>_<kwarg> format. Only arguments that were actually passed are included; unlike the DialectKWArgs.dialect_options collection, which contains all options known by this dialect including defaults.

The collection is also writable; keys are accepted of the form <dialect>_<kwarg> where the value will be assembled into the list of options.

New in version 0.9.2.

Changed in version 0.9.4: The DialectKWArgs.dialect_kwargs collection is now writable.

See also

DialectKWArgs.dialect_options - nested dictionary form

attribute sqlalchemy.sql.base.DialectKWArgs.dialect_options¶

A collection of keyword arguments specified as dialect-specific options to this construct.

This is a two-level nested registry, keyed to <dialect_name> and <argument_name>. For example, the postgresql_where argument would be locatable as:

arg = my_object.dialect_options['postgresql']['where']

New in version 0.9.2.

See also

DialectKWArgs.dialect_kwargs - flat dictionary form

attribute sqlalchemy.sql.base.DialectKWArgs.kwargs¶: A synonym for DialectKWArgs.dialect_kwargs.

class sqlalchemy.sql.expression.Extract(field, expr, **kwargs)¶

Represent a SQL EXTRACT clause, extract(field FROM expr).

Members

__init__(), get_children()

Class signature

class sqlalchemy.sql.expression.Extract (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Extract.__init__(field, expr, **kwargs)¶

Construct a new Extract object.

This constructor is mirrored as a public API function; see sqlalchemy.sql.expression.extract() for a full usage and argument description.

method sqlalchemy.sql.expression.Extract.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

class sqlalchemy.sql.elements.False_¶

Represent the false keyword, or equivalent, in a SQL statement.

False_ is accessed as a constant via the false() function.

Members

compare()

Class signature

class sqlalchemy.sql.expression.False_ (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.elements.False_.compare(other)¶

Compare this ColumnElement to another.

Special arguments understood:

Parameters:

use_proxies¶ – when True, consider two columns that share a common base column as equivalent (i.e. shares_lineage())
equivalents¶ – a dictionary of columns as keys mapped to sets of columns. If the given “other” column is present in this dictionary, if any of the columns in the corresponding set() pass the comparison test, the result is True. This is used to expand the comparison to other columns that may be known to be equivalent to this one via foreign key or other criterion.

class sqlalchemy.sql.expression.FunctionFilter(func, *criterion)¶

Represent a function FILTER clause.

This is a special operator against aggregate and window functions, which controls which rows are passed to it. It’s supported only by certain database backends.

Invocation of FunctionFilter is via FunctionElement.filter():

func.count(1).filter(True)

New in version 1.0.0.

See also

FunctionElement.filter()

Members

__init__(), filter(), get_children(), over(), self_group()

Class signature

class sqlalchemy.sql.expression.FunctionFilter (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.FunctionFilter.__init__(func, *criterion)¶

Construct a new FunctionFilter object.

This constructor is mirrored as a public API function; see sqlalchemy.sql.expression.funcfilter() for a full usage and argument description.

method sqlalchemy.sql.expression.FunctionFilter.filter(*criterion)¶

Produce an additional FILTER against the function.

This method adds additional criteria to the initial criteria set up by FunctionElement.filter().

Multiple criteria are joined together at SQL render time via AND.

method sqlalchemy.sql.expression.FunctionFilter.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

method sqlalchemy.sql.expression.FunctionFilter.over(partition_by=None, order_by=None, range_=None, rows=None)¶

Produce an OVER clause against this filtered function.

Used against aggregate or so-called “window” functions, for database backends that support window functions.

The expression:

func.rank().filter(MyClass.y > 5).over(order_by='x')

is shorthand for:

from sqlalchemy import over, funcfilter
over(funcfilter(func.rank(), MyClass.y > 5), order_by='x')

See over() for a full description.

method sqlalchemy.sql.expression.FunctionFilter.self_group(against=None)¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

class sqlalchemy.sql.expression.Label(name, element, type_=None)¶

Represents a column label (AS).

Represent a label, as typically applied to any column-level element using the AS sql keyword.

Members

__init__(), foreign_keys, get_children(), primary_key, self_group()

Class signature

class sqlalchemy.sql.expression.Label (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Label.__init__(name, element, type_=None)¶

Construct a new Label object.

This constructor is mirrored as a public API function; see sqlalchemy.sql.expression.label() for a full usage and argument description.

attribute sqlalchemy.sql.expression.Label.foreign_keys¶

method sqlalchemy.sql.expression.Label.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

attribute sqlalchemy.sql.expression.Label.primary_key¶

method sqlalchemy.sql.expression.Label.self_group(against=None)¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

class sqlalchemy.sql.elements.Null¶

Represent the NULL keyword in a SQL statement.

Null is accessed as a constant via the null() function.

Members

compare()

Class signature

class sqlalchemy.sql.expression.Null (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.elements.Null.compare(other)¶

Compare this ColumnElement to another.

Special arguments understood:

Parameters:

use_proxies¶ – when True, consider two columns that share a common base column as equivalent (i.e. shares_lineage())
equivalents¶ – a dictionary of columns as keys mapped to sets of columns. If the given “other” column is present in this dictionary, if any of the columns in the corresponding set() pass the comparison test, the result is True. This is used to expand the comparison to other columns that may be known to be equivalent to this one via foreign key or other criterion.

class sqlalchemy.sql.expression.Over(element, partition_by=None, order_by=None, range_=None, rows=None)¶

Represent an OVER clause.

This is a special operator against a so-called “window” function, as well as any aggregate function, which produces results relative to the result set itself. It’s supported only by certain database backends.

Members

__init__(), element, func, get_children()

Class signature

class sqlalchemy.sql.expression.Over (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Over.__init__(element, partition_by=None, order_by=None, range_=None, rows=None)¶

Construct a new Over object.

This constructor is mirrored as a public API function; see sqlalchemy.sql.expression.over() for a full usage and argument description.

attribute sqlalchemy.sql.expression.Over.element = None¶: The underlying expression object to which this Over object refers towards.

attribute sqlalchemy.sql.expression.Over.func¶: the element referred to by this Over clause.

Deprecated since version 1.1: the Over.func member of the Over class is deprecated and will be removed in a future release. Please refer to the Over.element attribute.

method sqlalchemy.sql.expression.Over.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

class sqlalchemy.sql.expression.TextClause(text, bind=None)¶

Represent a literal SQL text fragment.

E.g.:

from sqlalchemy import text

t = text("SELECT * FROM users")
result = connection.execute(t)

The TextClause construct is produced using the text() function; see that function for full documentation.

See also

text()

Members

bindparams(), columns(), compare(), get_children(), self_group()

Class signature

class sqlalchemy.sql.expression.TextClause (sqlalchemy.sql.expression.Executable, sqlalchemy.sql.expression.ClauseElement)

method sqlalchemy.sql.expression.TextClause.bindparams(*binds, **names_to_values)¶

Establish the values and/or types of bound parameters within this TextClause construct.

Given a text construct such as:

from sqlalchemy import text
stmt = text("SELECT id, name FROM user WHERE name=:name "
            "AND timestamp=:timestamp")

the TextClause.bindparams() method can be used to establish the initial value of :name and :timestamp, using simple keyword arguments:

stmt = stmt.bindparams(name='jack',
            timestamp=datetime.datetime(2012, 10, 8, 15, 12, 5))

Where above, new BindParameter objects will be generated with the names name and timestamp, and values of jack and datetime.datetime(2012, 10, 8, 15, 12, 5), respectively. The types will be inferred from the values given, in this case String and DateTime.

When specific typing behavior is needed, the positional *binds argument can be used in which to specify bindparam() constructs directly. These constructs must include at least the key argument, then an optional value and type:

from sqlalchemy import bindparam
stmt = stmt.bindparams(
                bindparam('name', value='jack', type_=String),
                bindparam('timestamp', type_=DateTime)
            )

Above, we specified the type of DateTime for the timestamp bind, and the type of String for the name bind. In the case of name we also set the default value of "jack".

Additional bound parameters can be supplied at statement execution time, e.g.:

result = connection.execute(stmt,
            timestamp=datetime.datetime(2012, 10, 8, 15, 12, 5))

The TextClause.bindparams() method can be called repeatedly, where it will re-use existing BindParameter objects to add new information. For example, we can call TextClause.bindparams() first with typing information, and a second time with value information, and it will be combined:

stmt = text("SELECT id, name FROM user WHERE name=:name "
            "AND timestamp=:timestamp")
stmt = stmt.bindparams(
    bindparam('name', type_=String),
    bindparam('timestamp', type_=DateTime)
)
stmt = stmt.bindparams(
    name='jack',
    timestamp=datetime.datetime(2012, 10, 8, 15, 12, 5)
)

The TextClause.bindparams() method also supports the concept of unique bound parameters. These are parameters that are “uniquified” on name at statement compilation time, so that multiple text() constructs may be combined together without the names conflicting. To use this feature, specify the BindParameter.unique flag on each bindparam() object:

stmt1 = text("select id from table where name=:name").bindparams(
    bindparam("name", value='name1', unique=True)
)
stmt2 = text("select id from table where name=:name").bindparams(
    bindparam("name", value='name2', unique=True)
)

union = union_all(
    stmt1.columns(column("id")),
    stmt2.columns(column("id"))
)

The above statement will render as:

select id from table where name=:name_1
UNION ALL select id from table where name=:name_2

New in version 1.3.11: Added support for the BindParameter.unique flag to work with text() constructs.

method sqlalchemy.sql.expression.TextClause.columns(selectable, *cols, **types)¶

Turn this TextClause object into a TextAsFrom object that can be embedded into another statement.

This function essentially bridges the gap between an entirely textual SELECT statement and the SQL expression language concept of a “selectable”:

from sqlalchemy.sql import column, text

stmt = text("SELECT id, name FROM some_table")
stmt = stmt.columns(column('id'), column('name')).alias('st')

stmt = select([mytable]).\
        select_from(
            mytable.join(stmt, mytable.c.name == stmt.c.name)
        ).where(stmt.c.id > 5)

Above, we pass a series of column() elements to the TextClause.columns() method positionally. These column() elements now become first class elements upon the TextAsFrom.c column collection, just like any other selectable.

The column expressions we pass to TextClause.columns() may also be typed; when we do so, these TypeEngine objects become the effective return type of the column, so that SQLAlchemy’s result-set-processing systems may be used on the return values. This is often needed for types such as date or boolean types, as well as for unicode processing on some dialect configurations:

stmt = text("SELECT id, name, timestamp FROM some_table")
stmt = stmt.columns(
            column('id', Integer),
            column('name', Unicode),
            column('timestamp', DateTime)
        )

for id, name, timestamp in connection.execute(stmt):
    print(id, name, timestamp)

As a shortcut to the above syntax, keyword arguments referring to types alone may be used, if only type conversion is needed:

stmt = text("SELECT id, name, timestamp FROM some_table")
stmt = stmt.columns(
            id=Integer,
            name=Unicode,
            timestamp=DateTime
        )

for id, name, timestamp in connection.execute(stmt):
    print(id, name, timestamp)

The positional form of TextClause.columns() also provides the unique feature of positional column targeting, which is particularly useful when using the ORM with complex textual queries. If we specify the columns from our model to TextClause.columns(), the result set will match to those columns positionally, meaning the name or origin of the column in the textual SQL doesn’t matter:

stmt = text("SELECT users.id, addresses.id, users.id, "
     "users.name, addresses.email_address AS email "
     "FROM users JOIN addresses ON users.id=addresses.user_id "
     "WHERE users.id = 1").columns(
        User.id,
        Address.id,
        Address.user_id,
        User.name,
        Address.email_address
     )

query = session.query(User).from_statement(stmt).options(
    contains_eager(User.addresses))

New in version 1.1: the TextClause.columns() method now offers positional column targeting in the result set when the column expressions are passed purely positionally.

The TextClause.columns() method provides a direct route to calling FromClause.alias() as well as SelectBase.cte() against a textual SELECT statement:

stmt = stmt.columns(id=Integer, name=String).cte('st')

stmt = select([sometable]).where(sometable.c.id == stmt.c.id)

New in version 0.9.0: text() can now be converted into a fully featured “selectable” construct using the TextClause.columns() method.

method sqlalchemy.sql.expression.TextClause.compare(other)¶

Compare this ClauseElement to the given ClauseElement.

Subclasses should override the default behavior, which is a straight identity comparison.

**kw are arguments consumed by subclass compare() methods and may be used to modify the criteria for comparison (see ColumnElement).

method sqlalchemy.sql.expression.TextClause.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

method sqlalchemy.sql.expression.TextClause.self_group(against=None)¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

class sqlalchemy.sql.expression.Tuple(*clauses, **kw)¶

Represent a SQL tuple.

Members

__init__()

Class signature

class sqlalchemy.sql.expression.Tuple (sqlalchemy.sql.expression.ClauseList, sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Tuple.__init__(*clauses, **kw)¶

Construct a new Tuple object.

This constructor is mirrored as a public API function; see sqlalchemy.sql.expression.tuple_() for a full usage and argument description.

class sqlalchemy.sql.expression.WithinGroup(element, *order_by)¶

Represent a WITHIN GROUP (ORDER BY) clause.

This is a special operator against so-called “ordered set aggregate” and “hypothetical set aggregate” functions, including percentile_cont(), rank(), dense_rank(), etc.

It’s supported only by certain database backends, such as PostgreSQL, Oracle and MS SQL Server.

The WithinGroup construct extracts its type from the method FunctionElement.within_group_type(). If this returns None, the function’s .type is used.

Members

__init__(), get_children(), over()

Class signature

class sqlalchemy.sql.expression.WithinGroup (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.WithinGroup.__init__(element, *order_by)¶

Construct a new WithinGroup object.

This constructor is mirrored as a public API function; see sqlalchemy.sql.expression.within_group() for a full usage and argument description.

method sqlalchemy.sql.expression.WithinGroup.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

method sqlalchemy.sql.expression.WithinGroup.over(partition_by=None, order_by=None, range_=None, rows=None)¶

Produce an OVER clause against this WithinGroup construct.

This function has the same signature as that of FunctionElement.over().

class sqlalchemy.sql.elements.True_¶

Represent the true keyword, or equivalent, in a SQL statement.

True_ is accessed as a constant via the true() function.

Members

compare()

Class signature

class sqlalchemy.sql.expression.True_ (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.elements.True_.compare(other)¶

Compare this ColumnElement to another.

Special arguments understood:

Parameters:

use_proxies¶ – when True, consider two columns that share a common base column as equivalent (i.e. shares_lineage())
equivalents¶ – a dictionary of columns as keys mapped to sets of columns. If the given “other” column is present in this dictionary, if any of the columns in the corresponding set() pass the comparison test, the result is True. This is used to expand the comparison to other columns that may be known to be equivalent to this one via foreign key or other criterion.

class sqlalchemy.sql.expression.TypeCoerce(expression, type_)¶

Represent a Python-side type-coercion wrapper.

TypeCoerce supplies the type_coerce() function; see that function for usage details.

Changed in version 1.1: The type_coerce() function now produces a persistent TypeCoerce wrapper object rather than translating the given object in place.

See also

type_coerce()

__init__(), get_children(), self_group()

Members

Class signature

class sqlalchemy.sql.expression.TypeCoerce (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.TypeCoerce.__init__(expression, type_)¶

Construct a new TypeCoerce object.

This constructor is mirrored as a public API function; see sqlalchemy.sql.expression.type_coerce() for a full usage and argument description.

method sqlalchemy.sql.expression.TypeCoerce.get_children(**kwargs)¶

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

method sqlalchemy.sql.expression.TypeCoerce.self_group(against=None)¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

class sqlalchemy.sql.operators.custom_op(opstring, precedence=0, is_comparison=False, return_type=None, natural_self_precedent=False, eager_grouping=False)¶

Represent a ‘custom’ operator.

custom_op is normally instantiated when the Operators.op() or Operators.bool_op() methods are used to create a custom operator callable. The class can also be used directly when programmatically constructing expressions. E.g. to represent the “factorial” operation:

from sqlalchemy.sql import UnaryExpression
from sqlalchemy.sql import operators
from sqlalchemy import Numeric

unary = UnaryExpression(table.c.somecolumn,
        modifier=operators.custom_op("!"),
        type_=Numeric)

See also

Operators.bool_op()

class sqlalchemy.sql.operators.Operators¶

Base of comparison and logical operators.

Implements base methods Operators.operate() and Operators.reverse_operate(), as well as Operators.__and__(), Operators.__or__(), Operators.__invert__().

Members

__and__(), __invert__(), __or__(), bool_op(), op(), operate(), reverse_operate()

Usually is used via its most common subclass ColumnOperators.

method sqlalchemy.sql.operators.Operators.__and__(other)¶

Implement the & operator.

When used with SQL expressions, results in an AND operation, equivalent to and_(), that is:

a & b

is equivalent to:

from sqlalchemy import and_
and_(a, b)

Care should be taken when using & regarding operator precedence; the & operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

(a == 2) & (b == 4)

method sqlalchemy.sql.operators.Operators.__invert__()¶

Implement the ~ operator.

When used with SQL expressions, results in a NOT operation, equivalent to not_(), that is:

~a

is equivalent to:

from sqlalchemy import not_
not_(a)

method sqlalchemy.sql.operators.Operators.__or__(other)¶

Implement the | operator.

When used with SQL expressions, results in an OR operation, equivalent to or_(), that is:

a | b

is equivalent to:

from sqlalchemy import or_
or_(a, b)

Care should be taken when using | regarding operator precedence; the | operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

(a == 2) | (b == 4)

method sqlalchemy.sql.operators.Operators.bool_op(opstring, precedence=0)¶

Return a custom boolean operator.

This method is shorthand for calling Operators.op() and passing the Operators.op.is_comparison flag with True.

New in version 1.2.0b3.

See also

method sqlalchemy.sql.operators.Operators.op(opstring, precedence=0, is_comparison=False, return_type=None)¶

Produce a generic operator function.

e.g.:

somecolumn.op("*")(5)

produces:

somecolumn * 5

This function can also be used to make bitwise operators explicit. For example:

somecolumn.op('&')(0xff)

is a bitwise AND of the value in somecolumn.

Parameters:

operator¶ – a string which will be output as the infix operator between this element and the expression passed to the generated function.
precedence¶ – precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of 0 is lower than all operators except for the comma (,) and AS operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators.
is_comparison¶ –
if True, the operator will be considered as a “comparison” operator, that is which evaluates to a boolean true/false value, like ==, >, etc. This flag should be set so that ORM relationships can establish that the operator is a comparison operator when used in a custom join condition.

New in version 0.9.2: - added the Operators.op.is_comparison flag.
return_type¶ –
a TypeEngine class or object that will force the return type of an expression produced by this operator to be of that type. By default, operators that specify Operators.op.is_comparison will resolve to Boolean, and those that do not will be of the same type as the left-hand operand.

New in version 1.2.0b3: - added the Operators.op.return_type argument.

See also