SQLAlchemy 1.3 Documentation
SQLAlchemy Core
- SQL Expression Language Tutorial
- SQL Statements and Expressions API
- Schema Definition Language
- Column and Data Types
- Engine and Connection Use
- Core API Basics
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Insert, Updates, Deletes¶
INSERT, UPDATE and DELETE statements build on a hierarchy starting
with UpdateBase
. The Insert
and Update
constructs build on the intermediary ValuesBase
.
Object Name | Description |
---|---|
delete(table[, whereclause, bind, returning, ...], **dialect_kw) |
Construct |
Represent a DELETE construct. |
|
insert(table[, values, inline, bind, ...], **dialect_kw) |
Construct an |
Represent an INSERT construct. |
|
update(table[, whereclause, values, inline, ...], **dialect_kw) |
Construct an |
Represent an Update construct. |
|
Form the base for |
|
Supplies support for |
- function sqlalchemy.sql.expression.delete(table, whereclause=None, bind=None, returning=None, prefixes=None, **dialect_kw)¶
Construct
Delete
object.Similar functionality is available via the
TableClause.delete()
method onTable
.- Parameters:
table¶ – The table to delete rows from.
whereclause¶ – Optional SQL expression describing the
WHERE
condition of theDELETE
statement; is equivalent to using the more modernDelete.where()
method to specify theWHERE
clause.
See also
Deletes - SQL Expression Tutorial
- function sqlalchemy.sql.expression.insert(table, values=None, inline=False, bind=None, prefixes=None, returning=None, return_defaults=False, **dialect_kw)¶
Construct an
Insert
object.Similar functionality is available via the
TableClause.insert()
method onTable
.- Parameters:
table¶ –
TableClause
which is the subject of the insert.values¶ – collection of values to be inserted; see
Insert.values()
for a description of allowed formats here. Can be omitted entirely; aInsert
construct will also dynamically render the VALUES clause at execution time based on the parameters passed toConnection.execute()
.inline¶ – if True, no attempt will be made to retrieve the SQL-generated default values to be provided within the statement; in particular, this allows SQL expressions to be rendered ‘inline’ within the statement without the need to pre-execute them beforehand; for backends that support “returning”, this turns off the “implicit returning” feature for the statement.
If both values and compile-time bind parameters are present, the compile-time bind parameters override the information specified within values on a per-key basis.
The keys within values can be either
Column
objects or their string identifiers. Each key may reference one of:a literal data value (i.e. string, number, etc.);
a Column object;
a SELECT statement.
If a
SELECT
statement is specified which references thisINSERT
statement’s table, the statement will be correlated against theINSERT
statement.See also
Insert Expressions - SQL Expression Tutorial
Inserts, Updates and Deletes - SQL Expression Tutorial
- function sqlalchemy.sql.expression.update(table, whereclause=None, values=None, inline=False, bind=None, prefixes=None, returning=None, return_defaults=False, preserve_parameter_order=False, **dialect_kw)¶
Construct an
Update
object.E.g.:
from sqlalchemy import update stmt = update(users).where(users.c.id==5).\ values(name='user #5')
Similar functionality is available via the
TableClause.update()
method onTable
:stmt = users.update().\ where(users.c.id==5).\ values(name='user #5')
- Parameters:
table¶ – A
Table
object representing the database table to be updated.whereclause¶ – Optional SQL expression describing the
WHERE
condition of theUPDATE
statement; is equivalent to using the more modernUpdate.where()
method to specify theWHERE
clause.values¶ –
Optional dictionary which specifies the
SET
conditions of theUPDATE
. If left asNone
, theSET
conditions are determined from those parameters passed to the statement during the execution and/or compilation of the statement. When compiled standalone without any parameters, theSET
clause generates for all columns.Modern applications may prefer to use the generative
Update.values()
method to set the values of the UPDATE statement.inline¶ – if True, SQL defaults present on
Column
objects via thedefault
keyword will be compiled ‘inline’ into the statement and not pre-executed. This means that their values will not be available in the dictionary returned fromResultProxy.last_updated_params()
.preserve_parameter_order¶ –
if True, the update statement is expected to receive parameters only via the
Update.values()
method, and they must be passed as a Pythonlist
of 2-tuples. The rendered UPDATE statement will emit the SET clause for each referenced column maintaining this order.New in version 1.0.10.
See also
Parameter-Ordered Updates - full example of the
update.preserve_parameter_order
flag
If both
values
and compile-time bind parameters are present, the compile-time bind parameters override the information specified withinvalues
on a per-key basis.The keys within
values
can be eitherColumn
objects or their string identifiers (specifically the “key” of theColumn
, normally but not necessarily equivalent to its “name”). Normally, theColumn
objects used here are expected to be part of the targetTable
that is the table to be updated. However when using MySQL, a multiple-table UPDATE statement can refer to columns from any of the tables referred to in the WHERE clause.The values referred to in
values
are typically:a literal data value (i.e. string, number, etc.)
a SQL expression, such as a related
Column
, a scalar-returningselect()
construct, etc.
When combining
select()
constructs within the values clause of anupdate()
construct, the subquery represented by theselect()
should be correlated to the parent table, that is, providing criterion which links the table inside the subquery to the outer table being updated:users.update().values( name=select([addresses.c.email_address]).\ where(addresses.c.user_id==users.c.id).\ as_scalar() )
See also
Inserts, Updates and Deletes - SQL Expression Language Tutorial
- class sqlalchemy.sql.expression.Delete(table, whereclause=None, bind=None, returning=None, prefixes=None, **dialect_kw)¶
Represent a DELETE construct.
The
Delete
object is created using thedelete()
function.Members
Class signature
class
sqlalchemy.sql.expression.Delete
(sqlalchemy.sql.expression.UpdateBase
)-
method
sqlalchemy.sql.expression.Delete.
returning(*cols)¶ inherited from the
UpdateBase.returning()
method ofUpdateBase
Add a RETURNING or equivalent clause to this statement.
e.g.:
stmt = table.update().\ where(table.c.data == 'value').\ values(status='X').\ returning(table.c.server_flag, table.c.updated_timestamp) for server_flag, updated_timestamp in connection.execute(stmt): print(server_flag, updated_timestamp)
The given collection of column expressions should be derived from the table that is the target of the INSERT, UPDATE, or DELETE. While
Column
objects are typical, the elements can also be expressions:stmt = table.insert().returning( (table.c.first_name + " " + table.c.last_name). label('fullname'))
Upon compilation, a RETURNING clause, or database equivalent, will be rendered within the statement. For INSERT and UPDATE, the values are the newly inserted/updated values. For DELETE, the values are those of the rows which were deleted.
Upon execution, the values of the columns to be returned are made available via the result set and can be iterated using
ResultProxy.fetchone()
and similar. For DBAPIs which do not natively support returning values (i.e. cx_oracle), SQLAlchemy will approximate this behavior at the result level so that a reasonable amount of behavioral neutrality is provided.Note that not all databases/DBAPIs support RETURNING. For those backends with no support, an exception is raised upon compilation and/or execution. For those who do support it, the functionality across backends varies greatly, including restrictions on executemany() and other statements which return multiple rows. Please read the documentation notes for the database in use in order to determine the availability of RETURNING.
See also
ValuesBase.return_defaults()
- an alternative method tailored towards efficient fetching of server-side defaults and triggers for single-row INSERTs or UPDATEs.
-
method
sqlalchemy.sql.expression.Delete.
__init__(table, whereclause=None, bind=None, returning=None, prefixes=None, **dialect_kw)¶ Construct a new
Delete
object.This constructor is mirrored as a public API function; see
sqlalchemy.sql.expression.delete()
for a full usage and argument description.
-
method
sqlalchemy.sql.expression.Delete.
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.Delete.
where(whereclause)¶ Add the given WHERE clause to a newly returned delete construct.
Both
Update.where()
andDelete.where()
support multiple-table forms, including database-specificUPDATE...FROM
as well asDELETE..USING
. For backends that don’t have multiple-table support, a backend agnostic approach to using multiple tables is to make use of correlated subqueries. See the linked tutorial sections below for examples.
-
method
- class sqlalchemy.sql.expression.Insert(table, values=None, inline=False, bind=None, prefixes=None, returning=None, return_defaults=False, **dialect_kw)¶
Represent an INSERT construct.
The
Insert
object is created using theinsert()
function.See also
Members
values(), returning(), __init__(), from_select(), get_children()
Class signature
class
sqlalchemy.sql.expression.Insert
(sqlalchemy.sql.expression.ValuesBase
)-
method
sqlalchemy.sql.expression.Insert.
values(*args, **kwargs)¶ inherited from the
ValuesBase.values()
method ofValuesBase
Specify a fixed VALUES clause for an INSERT statement, or the SET clause for an UPDATE.
Note that the
Insert
andUpdate
constructs support per-execution time formatting of the VALUES and/or SET clauses, based on the arguments passed toConnection.execute()
. However, theValuesBase.values()
method can be used to “fix” a particular set of parameters into the statement.Multiple calls to
ValuesBase.values()
will produce a new construct, each one with the parameter list modified to include the new parameters sent. In the typical case of a single dictionary of parameters, the newly passed keys will replace the same keys in the previous construct. In the case of a list-based “multiple values” construct, each new list of values is extended onto the existing list of values.- Parameters:
**kwargs¶ –
key value pairs representing the string key of a
Column
mapped to the value to be rendered into the VALUES or SET clause:users.insert().values(name="some name") users.update().where(users.c.id==5).values(name="some name")
*args¶ –
As an alternative to passing key/value parameters, a dictionary, tuple, or list of dictionaries or tuples can be passed as a single positional argument in order to form the VALUES or SET clause of the statement. The forms that are accepted vary based on whether this is an
Insert
or anUpdate
construct.For either an
Insert
orUpdate
construct, a single dictionary can be passed, which works the same as that of the kwargs form:users.insert().values({"name": "some name"}) users.update().values({"name": "some new name"})
Also for either form but more typically for the
Insert
construct, a tuple that contains an entry for every column in the table is also accepted:users.insert().values((5, "some name"))
The
Insert
construct also supports being passed a list of dictionaries or full-table-tuples, which on the server will render the less common SQL syntax of “multiple values” - this syntax is supported on backends such as SQLite, PostgreSQL, MySQL, but not necessarily others:users.insert().values([ {"name": "some name"}, {"name": "some other name"}, {"name": "yet another name"}, ])
The above form would render a multiple VALUES statement similar to:
INSERT INTO users (name) VALUES (:name_1), (:name_2), (:name_3)
It is essential to note that passing multiple values is NOT the same as using traditional executemany() form. The above syntax is a special syntax not typically used. To emit an INSERT statement against multiple rows, the normal method is to pass a multiple values list to the
Connection.execute()
method, which is supported by all database backends and is generally more efficient for a very large number of parameters.See also
Executing Multiple Statements - an introduction to the traditional Core method of multiple parameter set invocation for INSERTs and other statements.
Changed in version 1.0.0: an INSERT that uses a multiple-VALUES clause, even a list of length one, implies that the
Insert.inline
flag is set to True, indicating that the statement will not attempt to fetch the “last inserted primary key” or other defaults. The statement deals with an arbitrary number of rows, so theResultProxy.inserted_primary_key
accessor does not apply.Changed in version 1.0.0: A multiple-VALUES INSERT now supports columns with Python side default values and callables in the same way as that of an “executemany” style of invocation; the callable is invoked for each row. See Python-side defaults invoked for each row individually when using a multivalued insert for other details.
The
Update
construct supports a special form which is a list of 2-tuples, which when provided must be passed in conjunction with theupdate.preserve_parameter_order
parameter. This form causes the UPDATE statement to render the SET clauses using the order of parameters given toUpdate.values()
, rather than the ordering of columns given in theTable
.New in version 1.0.10: - added support for parameter-ordered UPDATE statements via the
update.preserve_parameter_order
flag.See also
Parameter-Ordered Updates - full example of the
update.preserve_parameter_order
flag
See also
Inserts, Updates and Deletes - SQL Expression Language Tutorial
insert()
- produce anINSERT
statementupdate()
- produce anUPDATE
statement
-
method
sqlalchemy.sql.expression.Insert.
returning(*cols)¶ inherited from the
UpdateBase.returning()
method ofUpdateBase
Add a RETURNING or equivalent clause to this statement.
e.g.:
stmt = table.update().\ where(table.c.data == 'value').\ values(status='X').\ returning(table.c.server_flag, table.c.updated_timestamp) for server_flag, updated_timestamp in connection.execute(stmt): print(server_flag, updated_timestamp)
The given collection of column expressions should be derived from the table that is the target of the INSERT, UPDATE, or DELETE. While
Column
objects are typical, the elements can also be expressions:stmt = table.insert().returning( (table.c.first_name + " " + table.c.last_name). label('fullname'))
Upon compilation, a RETURNING clause, or database equivalent, will be rendered within the statement. For INSERT and UPDATE, the values are the newly inserted/updated values. For DELETE, the values are those of the rows which were deleted.
Upon execution, the values of the columns to be returned are made available via the result set and can be iterated using
ResultProxy.fetchone()
and similar. For DBAPIs which do not natively support returning values (i.e. cx_oracle), SQLAlchemy will approximate this behavior at the result level so that a reasonable amount of behavioral neutrality is provided.Note that not all databases/DBAPIs support RETURNING. For those backends with no support, an exception is raised upon compilation and/or execution. For those who do support it, the functionality across backends varies greatly, including restrictions on executemany() and other statements which return multiple rows. Please read the documentation notes for the database in use in order to determine the availability of RETURNING.
See also
ValuesBase.return_defaults()
- an alternative method tailored towards efficient fetching of server-side defaults and triggers for single-row INSERTs or UPDATEs.
-
method
sqlalchemy.sql.expression.Insert.
__init__(table, values=None, inline=False, bind=None, prefixes=None, returning=None, return_defaults=False, **dialect_kw)¶ Construct a new
Insert
object.This constructor is mirrored as a public API function; see
sqlalchemy.sql.expression.insert()
for a full usage and argument description.
-
method
sqlalchemy.sql.expression.Insert.
from_select(names, select, include_defaults=True)¶ Return a new
Insert
construct which represents anINSERT...FROM SELECT
statement.e.g.:
sel = select([table1.c.a, table1.c.b]).where(table1.c.c > 5) ins = table2.insert().from_select(['a', 'b'], sel)
- Parameters:
names¶ – a sequence of string column names or
Column
objects representing the target columns.select¶ – a
select()
construct,FromClause
or other construct which resolves into aFromClause
, such as an ORMQuery
object, etc. The order of columns returned from this FROM clause should correspond to the order of columns sent as thenames
parameter; while this is not checked before passing along to the database, the database would normally raise an exception if these column lists don’t correspond.include_defaults¶ –
if True, non-server default values and SQL expressions as specified on
Column
objects (as documented in Column INSERT/UPDATE Defaults) not otherwise specified in the list of names will be rendered into the INSERT and SELECT statements, so that these values are also included in the data to be inserted.Note
A Python-side default that uses a Python callable function will only be invoked once for the whole statement, and not per row.
New in version 1.0.0: -
Insert.from_select()
now renders Python-side and SQL expression column defaults into the SELECT statement for columns otherwise not included in the list of column names.
Changed in version 1.0.0: an INSERT that uses FROM SELECT implies that the
insert.inline
flag is set to True, indicating that the statement will not attempt to fetch the “last inserted primary key” or other defaults. The statement deals with an arbitrary number of rows, so theResultProxy.inserted_primary_key
accessor does not apply.
-
method
sqlalchemy.sql.expression.Insert.
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
- class sqlalchemy.sql.expression.Update(table, whereclause=None, values=None, inline=False, bind=None, prefixes=None, returning=None, return_defaults=False, preserve_parameter_order=False, **dialect_kw)¶
Represent an Update construct.
The
Update
object is created using theupdate()
function.Members
Class signature
class
sqlalchemy.sql.expression.Update
(sqlalchemy.sql.expression.ValuesBase
)-
method
sqlalchemy.sql.expression.Update.
returning(*cols)¶ inherited from the
UpdateBase.returning()
method ofUpdateBase
Add a RETURNING or equivalent clause to this statement.
e.g.:
stmt = table.update().\ where(table.c.data == 'value').\ values(status='X').\ returning(table.c.server_flag, table.c.updated_timestamp) for server_flag, updated_timestamp in connection.execute(stmt): print(server_flag, updated_timestamp)
The given collection of column expressions should be derived from the table that is the target of the INSERT, UPDATE, or DELETE. While
Column
objects are typical, the elements can also be expressions:stmt = table.insert().returning( (table.c.first_name + " " + table.c.last_name). label('fullname'))
Upon compilation, a RETURNING clause, or database equivalent, will be rendered within the statement. For INSERT and UPDATE, the values are the newly inserted/updated values. For DELETE, the values are those of the rows which were deleted.
Upon execution, the values of the columns to be returned are made available via the result set and can be iterated using
ResultProxy.fetchone()
and similar. For DBAPIs which do not natively support returning values (i.e. cx_oracle), SQLAlchemy will approximate this behavior at the result level so that a reasonable amount of behavioral neutrality is provided.Note that not all databases/DBAPIs support RETURNING. For those backends with no support, an exception is raised upon compilation and/or execution. For those who do support it, the functionality across backends varies greatly, including restrictions on executemany() and other statements which return multiple rows. Please read the documentation notes for the database in use in order to determine the availability of RETURNING.
See also
ValuesBase.return_defaults()
- an alternative method tailored towards efficient fetching of server-side defaults and triggers for single-row INSERTs or UPDATEs.
-
method
sqlalchemy.sql.expression.Update.
values(*args, **kwargs)¶ inherited from the
ValuesBase.values()
method ofValuesBase
Specify a fixed VALUES clause for an INSERT statement, or the SET clause for an UPDATE.
Note that the
Insert
andUpdate
constructs support per-execution time formatting of the VALUES and/or SET clauses, based on the arguments passed toConnection.execute()
. However, theValuesBase.values()
method can be used to “fix” a particular set of parameters into the statement.Multiple calls to
ValuesBase.values()
will produce a new construct, each one with the parameter list modified to include the new parameters sent. In the typical case of a single dictionary of parameters, the newly passed keys will replace the same keys in the previous construct. In the case of a list-based “multiple values” construct, each new list of values is extended onto the existing list of values.- Parameters:
**kwargs¶ –
key value pairs representing the string key of a
Column
mapped to the value to be rendered into the VALUES or SET clause:users.insert().values(name="some name") users.update().where(users.c.id==5).values(name="some name")
*args¶ –
As an alternative to passing key/value parameters, a dictionary, tuple, or list of dictionaries or tuples can be passed as a single positional argument in order to form the VALUES or SET clause of the statement. The forms that are accepted vary based on whether this is an
Insert
or anUpdate
construct.For either an
Insert
orUpdate
construct, a single dictionary can be passed, which works the same as that of the kwargs form:users.insert().values({"name": "some name"}) users.update().values({"name": "some new name"})
Also for either form but more typically for the
Insert
construct, a tuple that contains an entry for every column in the table is also accepted:users.insert().values((5, "some name"))
The
Insert
construct also supports being passed a list of dictionaries or full-table-tuples, which on the server will render the less common SQL syntax of “multiple values” - this syntax is supported on backends such as SQLite, PostgreSQL, MySQL, but not necessarily others:users.insert().values([ {"name": "some name"}, {"name": "some other name"}, {"name": "yet another name"}, ])
The above form would render a multiple VALUES statement similar to:
INSERT INTO users (name) VALUES (:name_1), (:name_2), (:name_3)
It is essential to note that passing multiple values is NOT the same as using traditional executemany() form. The above syntax is a special syntax not typically used. To emit an INSERT statement against multiple rows, the normal method is to pass a multiple values list to the
Connection.execute()
method, which is supported by all database backends and is generally more efficient for a very large number of parameters.See also
Executing Multiple Statements - an introduction to the traditional Core method of multiple parameter set invocation for INSERTs and other statements.
Changed in version 1.0.0: an INSERT that uses a multiple-VALUES clause, even a list of length one, implies that the
Insert.inline
flag is set to True, indicating that the statement will not attempt to fetch the “last inserted primary key” or other defaults. The statement deals with an arbitrary number of rows, so theResultProxy.inserted_primary_key
accessor does not apply.Changed in version 1.0.0: A multiple-VALUES INSERT now supports columns with Python side default values and callables in the same way as that of an “executemany” style of invocation; the callable is invoked for each row. See Python-side defaults invoked for each row individually when using a multivalued insert for other details.
The
Update
construct supports a special form which is a list of 2-tuples, which when provided must be passed in conjunction with theupdate.preserve_parameter_order
parameter. This form causes the UPDATE statement to render the SET clauses using the order of parameters given toUpdate.values()
, rather than the ordering of columns given in theTable
.New in version 1.0.10: - added support for parameter-ordered UPDATE statements via the
update.preserve_parameter_order
flag.See also
Parameter-Ordered Updates - full example of the
update.preserve_parameter_order
flag
See also
Inserts, Updates and Deletes - SQL Expression Language Tutorial
insert()
- produce anINSERT
statementupdate()
- produce anUPDATE
statement
-
method
sqlalchemy.sql.expression.Update.
__init__(table, whereclause=None, values=None, inline=False, bind=None, prefixes=None, returning=None, return_defaults=False, preserve_parameter_order=False, **dialect_kw)¶ Construct a new
Update
object.This constructor is mirrored as a public API function; see
sqlalchemy.sql.expression.update()
for a full usage and argument description.
-
method
sqlalchemy.sql.expression.Update.
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.Update.
where(whereclause)¶ Return a new update() construct with the given expression added to its WHERE clause, joined to the existing clause via AND, if any.
Both
Update.where()
andDelete.where()
support multiple-table forms, including database-specificUPDATE...FROM
as well asDELETE..USING
. For backends that don’t have multiple-table support, a backend agnostic approach to using multiple tables is to make use of correlated subqueries. See the linked tutorial sections below for examples.
-
method
- class sqlalchemy.sql.expression.UpdateBase¶
Form the base for
INSERT
,UPDATE
, andDELETE
statements.Members
Class signature
class
sqlalchemy.sql.expression.UpdateBase
(sqlalchemy.sql.expression.HasCTE
,sqlalchemy.sql.base.DialectKWArgs
,sqlalchemy.sql.expression.HasPrefixes
,sqlalchemy.sql.expression.Executable
,sqlalchemy.sql.expression.ClauseElement
)-
attribute
sqlalchemy.sql.expression.UpdateBase.
bind¶ Return a ‘bind’ linked to this
UpdateBase
or aTable
associated with it.
-
method
sqlalchemy.sql.expression.UpdateBase.
params(*arg, **kw)¶ Set the parameters for the statement.
This method raises
NotImplementedError
on the base class, and is overridden byValuesBase
to provide the SET/VALUES clause of UPDATE and INSERT.
-
method
sqlalchemy.sql.expression.UpdateBase.
returning(*cols)¶ Add a RETURNING or equivalent clause to this statement.
e.g.:
stmt = table.update().\ where(table.c.data == 'value').\ values(status='X').\ returning(table.c.server_flag, table.c.updated_timestamp) for server_flag, updated_timestamp in connection.execute(stmt): print(server_flag, updated_timestamp)
The given collection of column expressions should be derived from the table that is the target of the INSERT, UPDATE, or DELETE. While
Column
objects are typical, the elements can also be expressions:stmt = table.insert().returning( (table.c.first_name + " " + table.c.last_name). label('fullname'))
Upon compilation, a RETURNING clause, or database equivalent, will be rendered within the statement. For INSERT and UPDATE, the values are the newly inserted/updated values. For DELETE, the values are those of the rows which were deleted.
Upon execution, the values of the columns to be returned are made available via the result set and can be iterated using
ResultProxy.fetchone()
and similar. For DBAPIs which do not natively support returning values (i.e. cx_oracle), SQLAlchemy will approximate this behavior at the result level so that a reasonable amount of behavioral neutrality is provided.Note that not all databases/DBAPIs support RETURNING. For those backends with no support, an exception is raised upon compilation and/or execution. For those who do support it, the functionality across backends varies greatly, including restrictions on executemany() and other statements which return multiple rows. Please read the documentation notes for the database in use in order to determine the availability of RETURNING.
See also
ValuesBase.return_defaults()
- an alternative method tailored towards efficient fetching of server-side defaults and triggers for single-row INSERTs or UPDATEs.
-
method
sqlalchemy.sql.expression.UpdateBase.
with_hint(text, selectable=None, dialect_name='*')¶ Add a table hint for a single table to this INSERT/UPDATE/DELETE statement.
Note
UpdateBase.with_hint()
currently applies only to Microsoft SQL Server. For MySQL INSERT/UPDATE/DELETE hints, useUpdateBase.prefix_with()
.The text of the hint is rendered in the appropriate location for the database backend in use, relative to the
Table
that is the subject of this statement, or optionally to that of the givenTable
passed as theselectable
argument.The
dialect_name
option will limit the rendering of a particular hint to a particular backend. Such as, to add a hint that only takes effect for SQL Server:mytable.insert().with_hint("WITH (PAGLOCK)", dialect_name="mssql")
- Parameters:
text¶ – Text of the hint.
selectable¶ – optional
Table
that specifies an element of the FROM clause within an UPDATE or DELETE to be the subject of the hint - applies only to certain backends.dialect_name¶ – defaults to
*
, if specified as the name of a particular dialect, will apply these hints only when that dialect is in use.
-
attribute
- class sqlalchemy.sql.expression.ValuesBase(table, values, prefixes)¶
Supplies support for
ValuesBase.values()
to INSERT and UPDATE constructs.Members
Class signature
class
sqlalchemy.sql.expression.ValuesBase
(sqlalchemy.sql.expression.UpdateBase
)-
method
sqlalchemy.sql.expression.ValuesBase.
return_defaults(*cols)¶ Make use of a RETURNING clause for the purpose of fetching server-side expressions and defaults.
E.g.:
stmt = table.insert().values(data='newdata').return_defaults() result = connection.execute(stmt) server_created_at = result.returned_defaults['created_at']
When used against a backend that supports RETURNING, all column values generated by SQL expression or server-side-default will be added to any existing RETURNING clause, provided that
UpdateBase.returning()
is not used simultaneously. The column values will then be available on the result using theResultProxy.returned_defaults
accessor as a dictionary, referring to values keyed to theColumn
object as well as its.key
.This method differs from
UpdateBase.returning()
in these ways:ValuesBase.return_defaults()
is only intended for use with an INSERT or an UPDATE statement that matches exactly one row. While the RETURNING construct in the general sense supports multiple rows for a multi-row UPDATE or DELETE statement, or for special cases of INSERT that return multiple rows (e.g. INSERT from SELECT, multi-valued VALUES clause),ValuesBase.return_defaults()
is intended only for an “ORM-style” single-row INSERT/UPDATE statement. The row returned by the statement is also consumed implicitly whenValuesBase.return_defaults()
is used. By contrast,UpdateBase.returning()
leaves the RETURNING result-set intact with a collection of any number of rows.It is compatible with the existing logic to fetch auto-generated primary key values, also known as “implicit returning”. Backends that support RETURNING will automatically make use of RETURNING in order to fetch the value of newly generated primary keys; while the
UpdateBase.returning()
method circumvents this behavior,ValuesBase.return_defaults()
leaves it intact.It can be called against any backend. Backends that don’t support RETURNING will skip the usage of the feature, rather than raising an exception. The return value of
ResultProxy.returned_defaults
will beNone
ValuesBase.return_defaults()
is used by the ORM to provide an efficient implementation for theeager_defaults
feature ofmapper()
.- Parameters:
cols¶ – optional list of column key names or
Column
objects. If omitted, all column expressions evaluated on the server are added to the returning list.
New in version 0.9.0.
-
method
sqlalchemy.sql.expression.ValuesBase.
values(*args, **kwargs)¶ Specify a fixed VALUES clause for an INSERT statement, or the SET clause for an UPDATE.
Note that the
Insert
andUpdate
constructs support per-execution time formatting of the VALUES and/or SET clauses, based on the arguments passed toConnection.execute()
. However, theValuesBase.values()
method can be used to “fix” a particular set of parameters into the statement.Multiple calls to
ValuesBase.values()
will produce a new construct, each one with the parameter list modified to include the new parameters sent. In the typical case of a single dictionary of parameters, the newly passed keys will replace the same keys in the previous construct. In the case of a list-based “multiple values” construct, each new list of values is extended onto the existing list of values.- Parameters:
**kwargs¶ –
key value pairs representing the string key of a
Column
mapped to the value to be rendered into the VALUES or SET clause:users.insert().values(name="some name") users.update().where(users.c.id==5).values(name="some name")
*args¶ –
As an alternative to passing key/value parameters, a dictionary, tuple, or list of dictionaries or tuples can be passed as a single positional argument in order to form the VALUES or SET clause of the statement. The forms that are accepted vary based on whether this is an
Insert
or anUpdate
construct.For either an
Insert
orUpdate
construct, a single dictionary can be passed, which works the same as that of the kwargs form:users.insert().values({"name": "some name"}) users.update().values({"name": "some new name"})
Also for either form but more typically for the
Insert
construct, a tuple that contains an entry for every column in the table is also accepted:users.insert().values((5, "some name"))
The
Insert
construct also supports being passed a list of dictionaries or full-table-tuples, which on the server will render the less common SQL syntax of “multiple values” - this syntax is supported on backends such as SQLite, PostgreSQL, MySQL, but not necessarily others:users.insert().values([ {"name": "some name"}, {"name": "some other name"}, {"name": "yet another name"}, ])
The above form would render a multiple VALUES statement similar to:
INSERT INTO users (name) VALUES (:name_1), (:name_2), (:name_3)
It is essential to note that passing multiple values is NOT the same as using traditional executemany() form. The above syntax is a special syntax not typically used. To emit an INSERT statement against multiple rows, the normal method is to pass a multiple values list to the
Connection.execute()
method, which is supported by all database backends and is generally more efficient for a very large number of parameters.See also
Executing Multiple Statements - an introduction to the traditional Core method of multiple parameter set invocation for INSERTs and other statements.
Changed in version 1.0.0: an INSERT that uses a multiple-VALUES clause, even a list of length one, implies that the
Insert.inline
flag is set to True, indicating that the statement will not attempt to fetch the “last inserted primary key” or other defaults. The statement deals with an arbitrary number of rows, so theResultProxy.inserted_primary_key
accessor does not apply.Changed in version 1.0.0: A multiple-VALUES INSERT now supports columns with Python side default values and callables in the same way as that of an “executemany” style of invocation; the callable is invoked for each row. See Python-side defaults invoked for each row individually when using a multivalued insert for other details.
The
Update
construct supports a special form which is a list of 2-tuples, which when provided must be passed in conjunction with theupdate.preserve_parameter_order
parameter. This form causes the UPDATE statement to render the SET clauses using the order of parameters given toUpdate.values()
, rather than the ordering of columns given in theTable
.New in version 1.0.10: - added support for parameter-ordered UPDATE statements via the
update.preserve_parameter_order
flag.See also
Parameter-Ordered Updates - full example of the
update.preserve_parameter_order
flag
See also
Inserts, Updates and Deletes - SQL Expression Language Tutorial
insert()
- produce anINSERT
statementupdate()
- produce anUPDATE
statement
-
method
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