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 |
---|---|
|
Construct |
Represent a DELETE construct. |
|
|
Construct an |
Represent an INSERT construct. |
|
|
Construct an |
Represent an Update construct. |
|
Form the base for |
|
Supplies support for |
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 on
Table
.
table¶ – The table to delete rows from.
whereclause¶ – Optional SQL expression describing the WHERE
condition of the DELETE
statement; is equivalent to using the
more modern Delete.where()
method to specify the WHERE
clause.
See also
Deletes - SQL Expression Tutorial
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 on
Table
.
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; a Insert
construct
will also dynamically render the VALUES clause at execution time
based on the parameters passed to Connection.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 this
INSERT
statement’s table, the statement will be correlated
against the INSERT
statement.
See also
Insert Expressions - SQL Expression Tutorial
Inserts, Updates and Deletes - SQL Expression Tutorial
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 on
Table
:
stmt = users.update().\
where(users.c.id==5).\
values(name='user #5')
table¶ – A Table
object representing the database
table to be updated.
whereclause¶ – Optional SQL expression describing the WHERE
condition of the UPDATE
statement; is equivalent to using the
more modern Update.where()
method to specify the WHERE
clause.
values¶ –
Optional dictionary which specifies the SET
conditions of the
UPDATE
. If left as None
, the SET
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,
the SET
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
the default
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 from
ResultProxy.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 Python
list
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
within values
on a per-key basis.
The keys within values
can be either Column
objects or their string identifiers (specifically the “key” of the
Column
, normally but not necessarily equivalent to
its “name”). Normally, the
Column
objects used here are expected to be
part of the target Table
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-returning select()
construct,
etc.
When combining select()
constructs within the values
clause of an update()
construct,
the subquery represented by the select()
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
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 the delete()
function.
Class signature
class sqlalchemy.sql.expression.Delete
(sqlalchemy.sql.expression.UpdateBase
)
sqlalchemy.sql.expression.Delete.
returning
(*cols)¶inherited from the UpdateBase.returning()
method of UpdateBase
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.
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.
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).
sqlalchemy.sql.expression.Delete.
where
(whereclause)¶Add the given WHERE clause to a newly returned delete construct.
Both Update.where()
and Delete.where()
support multiple-table forms, including database-specific
UPDATE...FROM
as well as DELETE..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.
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 the
insert()
function.
See also
Class signature
class sqlalchemy.sql.expression.Insert
(sqlalchemy.sql.expression.ValuesBase
)
sqlalchemy.sql.expression.Insert.
values
(*args, **kwargs)¶inherited from the ValuesBase.values()
method of ValuesBase
Specify a fixed VALUES clause for an INSERT statement, or the SET clause for an UPDATE.
Note that the Insert
and
Update
constructs support
per-execution time formatting of the VALUES and/or SET clauses,
based on the arguments passed to Connection.execute()
.
However, the ValuesBase.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.
**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 an
Update
construct.
For either an Insert
or
Update
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 the
update.preserve_parameter_order
parameter.
This form causes the UPDATE statement to render the SET clauses
using the order of parameters given to
Update.values()
, rather
than the ordering of columns given in the Table
.
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 an INSERT
statement
update()
- produce an UPDATE
statement
sqlalchemy.sql.expression.Insert.
returning
(*cols)¶inherited from the UpdateBase.returning()
method of UpdateBase
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.
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.
sqlalchemy.sql.expression.Insert.
from_select
(names, select, include_defaults=True)¶Return a new Insert
construct which represents
an INSERT...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)
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 a
FromClause
,
such as an ORM Query
object, etc. The order of
columns returned from this FROM clause should correspond to the
order of columns sent as the names
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 the
ResultProxy.inserted_primary_key
accessor does not apply.
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).
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 the update()
function.
Class signature
class sqlalchemy.sql.expression.Update
(sqlalchemy.sql.expression.ValuesBase
)
sqlalchemy.sql.expression.Update.
returning
(*cols)¶inherited from the UpdateBase.returning()
method of UpdateBase
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.
sqlalchemy.sql.expression.Update.
values
(*args, **kwargs)¶inherited from the ValuesBase.values()
method of ValuesBase
Specify a fixed VALUES clause for an INSERT statement, or the SET clause for an UPDATE.
Note that the Insert
and
Update
constructs support
per-execution time formatting of the VALUES and/or SET clauses,
based on the arguments passed to Connection.execute()
.
However, the ValuesBase.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.
**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 an
Update
construct.
For either an Insert
or
Update
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 the
update.preserve_parameter_order
parameter.
This form causes the UPDATE statement to render the SET clauses
using the order of parameters given to
Update.values()
, rather
than the ordering of columns given in the Table
.
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 an INSERT
statement
update()
- produce an UPDATE
statement
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.
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).
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()
and Delete.where()
support multiple-table forms, including database-specific
UPDATE...FROM
as well as DELETE..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.
sqlalchemy.sql.expression.
UpdateBase
¶Form the base for INSERT
, UPDATE
, and DELETE
statements.
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
)
sqlalchemy.sql.expression.UpdateBase.
bind
¶Return a ‘bind’ linked to this UpdateBase
or a Table
associated with it.
sqlalchemy.sql.expression.UpdateBase.
params
(*arg, **kw)¶Set the parameters for the statement.
This method raises NotImplementedError
on the base class,
and is overridden by ValuesBase
to provide the
SET/VALUES clause of UPDATE and INSERT.
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.
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, use
UpdateBase.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 given
Table
passed as the selectable
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")
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.
sqlalchemy.sql.expression.
ValuesBase
(table, values, prefixes)¶Supplies support for ValuesBase.values()
to
INSERT and UPDATE constructs.
Class signature
class sqlalchemy.sql.expression.ValuesBase
(sqlalchemy.sql.expression.UpdateBase
)
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 the
ResultProxy.returned_defaults
accessor as
a dictionary,
referring to values keyed to the Column
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 when
ValuesBase.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 be None
ValuesBase.return_defaults()
is used by the ORM to provide
an efficient implementation for the eager_defaults
feature of
mapper()
.
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.
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
and
Update
constructs support
per-execution time formatting of the VALUES and/or SET clauses,
based on the arguments passed to Connection.execute()
.
However, the ValuesBase.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.
**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 an
Update
construct.
For either an Insert
or
Update
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 the
update.preserve_parameter_order
parameter.
This form causes the UPDATE statement to render the SET clauses
using the order of parameters given to
Update.values()
, rather
than the ordering of columns given in the Table
.
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 an INSERT
statement
update()
- produce an UPDATE
statement
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