Current File : //opt/cloudlinux/venv/lib/python3.11/site-packages/sqlalchemy/sql/dml.py
# sql/dml.py
# Copyright (C) 2009-2021 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""
Provide :class:`_expression.Insert`, :class:`_expression.Update` and
:class:`_expression.Delete`.
"""
from . import util as sql_util
from .base import _from_objects
from .base import _generative
from .base import DialectKWArgs
from .base import Executable
from .elements import _clone
from .elements import _column_as_key
from .elements import _literal_as_text
from .elements import and_
from .elements import ClauseElement
from .elements import Null
from .selectable import _interpret_as_from
from .selectable import _interpret_as_select
from .selectable import HasCTE
from .selectable import HasPrefixes
from .. import exc
from .. import util
class UpdateBase(
HasCTE, DialectKWArgs, HasPrefixes, Executable, ClauseElement
):
"""Form the base for ``INSERT``, ``UPDATE``, and ``DELETE`` statements."""
__visit_name__ = "update_base"
_execution_options = Executable._execution_options.union(
{"autocommit": True}
)
_hints = util.immutabledict()
_parameter_ordering = None
_prefixes = ()
named_with_column = False
_return_defaults = None
def _process_colparams(self, parameters):
def process_single(p):
if isinstance(p, (list, tuple)):
return dict((c.key, pval) for c, pval in zip(self.table.c, p))
else:
return p
if self._preserve_parameter_order and parameters is not None:
if not isinstance(parameters, list) or (
parameters and not isinstance(parameters[0], tuple)
):
raise ValueError(
"When preserve_parameter_order is True, "
"values() only accepts a list of 2-tuples"
)
self._parameter_ordering = [key for key, value in parameters]
return dict(parameters), False
if (
isinstance(parameters, (list, tuple))
and parameters
and isinstance(parameters[0], (list, tuple, dict))
):
if not self._supports_multi_parameters:
raise exc.InvalidRequestError(
"This construct does not support "
"multiple parameter sets."
)
return [process_single(p) for p in parameters], True
else:
return process_single(parameters), False
def params(self, *arg, **kw):
"""Set the parameters for the statement.
This method raises ``NotImplementedError`` on the base class,
and is overridden by :class:`.ValuesBase` to provide the
SET/VALUES clause of UPDATE and INSERT.
"""
raise NotImplementedError(
"params() is not supported for INSERT/UPDATE/DELETE statements."
" To set the values for an INSERT or UPDATE statement, use"
" stmt.values(**parameters)."
)
def bind(self):
"""Return a 'bind' linked to this :class:`.UpdateBase`
or a :class:`_schema.Table` associated with it.
"""
return self._bind or self.table.bind
def _set_bind(self, bind):
self._bind = bind
bind = property(bind, _set_bind)
@_generative
def returning(self, *cols):
r"""Add a :term:`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
:class:`_schema.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
:meth:`_engine.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.
.. seealso::
:meth:`.ValuesBase.return_defaults` - an alternative method tailored
towards efficient fetching of server-side defaults and triggers
for single-row INSERTs or UPDATEs.
"""
if self._return_defaults:
raise exc.InvalidRequestError(
"return_defaults() is already configured on this statement"
)
if self._returning:
util.warn(
"The returning() method does not currently support multiple "
"additive calls. The existing RETURNING clause being "
"replaced by new columns."
)
self._returning = cols
@_generative
def with_hint(self, text, selectable=None, dialect_name="*"):
"""Add a table hint for a single table to this
INSERT/UPDATE/DELETE statement.
.. note::
:meth:`.UpdateBase.with_hint` currently applies only to
Microsoft SQL Server. For MySQL INSERT/UPDATE/DELETE hints, use
:meth:`.UpdateBase.prefix_with`.
The text of the hint is rendered in the appropriate
location for the database backend in use, relative
to the :class:`_schema.Table` that is the subject of this
statement, or optionally to that of the given
:class:`_schema.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")
:param text: Text of the hint.
:param selectable: optional :class:`_schema.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.
:param dialect_name: defaults to ``*``, if specified as the name
of a particular dialect, will apply these hints only when
that dialect is in use.
"""
if selectable is None:
selectable = self.table
self._hints = self._hints.union({(selectable, dialect_name): text})
class ValuesBase(UpdateBase):
"""Supplies support for :meth:`.ValuesBase.values` to
INSERT and UPDATE constructs."""
__visit_name__ = "values_base"
_supports_multi_parameters = False
_has_multi_parameters = False
_preserve_parameter_order = False
select = None
_post_values_clause = None
def __init__(self, table, values, prefixes):
self.table = _interpret_as_from(table)
self.parameters, self._has_multi_parameters = self._process_colparams(
values
)
if prefixes:
self._setup_prefixes(prefixes)
@_generative
def values(self, *args, **kwargs):
r"""Specify a fixed VALUES clause for an INSERT statement, or the SET
clause for an UPDATE.
Note that the :class:`_expression.Insert` and
:class:`_expression.Update` constructs support
per-execution time formatting of the VALUES and/or SET clauses,
based on the arguments passed to :meth:`_engine.Connection.execute`.
However, the :meth:`.ValuesBase.values` method can be used to "fix" a
particular set of parameters into the statement.
Multiple calls to :meth:`.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.
:param \**kwargs: key value pairs representing the string key
of a :class:`_schema.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")
:param \*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 :class:`_expression.Insert` or an
:class:`_expression.Update` construct.
For either an :class:`_expression.Insert` or
:class:`_expression.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
:class:`_expression.Insert` construct, a tuple that contains an
entry for every column in the table is also accepted::
users.insert().values((5, "some name"))
The :class:`_expression.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
:meth:`_engine.Connection.execute`
method, which is supported by all database backends and is generally
more efficient for a very large number of parameters.
.. seealso::
:ref:`execute_multiple` - an introduction to
the traditional Core method of multiple parameter set
invocation for INSERTs and other statements.
.. versionchanged:: 1.0.0 an INSERT that uses a multiple-VALUES
clause, even a list of length one,
implies that the :paramref:`_expression.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
:attr:`_engine.ResultProxy.inserted_primary_key`
accessor does not
apply.
.. versionchanged:: 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 :ref:`bug_3288`
for other details.
The :class:`_expression.Update`
construct supports a special form which is a
list of 2-tuples, which when provided must be passed in conjunction
with the
:paramref:`_expression.update.preserve_parameter_order`
parameter.
This form causes the UPDATE statement to render the SET clauses
using the order of parameters given to
:meth:`_expression.Update.values`, rather
than the ordering of columns given in the :class:`_schema.Table`.
.. versionadded:: 1.0.10 - added support for parameter-ordered
UPDATE statements via the
:paramref:`_expression.update.preserve_parameter_order`
flag.
.. seealso::
:ref:`updates_order_parameters` - full example of the
:paramref:`_expression.update.preserve_parameter_order`
flag
.. seealso::
:ref:`inserts_and_updates` - SQL Expression
Language Tutorial
:func:`_expression.insert` - produce an ``INSERT`` statement
:func:`_expression.update` - produce an ``UPDATE`` statement
"""
if self.select is not None:
raise exc.InvalidRequestError(
"This construct already inserts from a SELECT"
)
if self._has_multi_parameters and kwargs:
raise exc.InvalidRequestError(
"This construct already has multiple parameter sets."
)
if args:
if len(args) > 1:
raise exc.ArgumentError(
"Only a single dictionary/tuple or list of "
"dictionaries/tuples is accepted positionally."
)
v = args[0]
else:
v = {}
if self.parameters is None:
(
self.parameters,
self._has_multi_parameters,
) = self._process_colparams(v)
else:
if self._has_multi_parameters:
self.parameters = list(self.parameters)
p, self._has_multi_parameters = self._process_colparams(v)
if not self._has_multi_parameters:
raise exc.ArgumentError(
"Can't mix single-values and multiple values "
"formats in one statement"
)
self.parameters.extend(p)
else:
self.parameters = self.parameters.copy()
p, self._has_multi_parameters = self._process_colparams(v)
if self._has_multi_parameters:
raise exc.ArgumentError(
"Can't mix single-values and multiple values "
"formats in one statement"
)
self.parameters.update(p)
if kwargs:
if self._has_multi_parameters:
raise exc.ArgumentError(
"Can't pass kwargs and multiple parameter sets "
"simultaneously"
)
else:
self.parameters.update(kwargs)
@_generative
def return_defaults(self, *cols):
"""Make use of a :term:`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
:meth:`.UpdateBase.returning` is not used simultaneously. The column
values will then be available on the result using the
:attr:`_engine.ResultProxy.returned_defaults` accessor as
a dictionary,
referring to values keyed to the :class:`_schema.Column`
object as well as
its ``.key``.
This method differs from :meth:`.UpdateBase.returning` in these ways:
1. :meth:`.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),
:meth:`.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
:meth:`.ValuesBase.return_defaults` is used. By contrast,
:meth:`.UpdateBase.returning` leaves the RETURNING result-set
intact with a collection of any number of rows.
2. 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
:meth:`.UpdateBase.returning` method circumvents this behavior,
:meth:`.ValuesBase.return_defaults` leaves it intact.
3. 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
:attr:`_engine.ResultProxy.returned_defaults` will be ``None``
:meth:`.ValuesBase.return_defaults` is used by the ORM to provide
an efficient implementation for the ``eager_defaults`` feature of
:func:`.mapper`.
:param cols: optional list of column key names or
:class:`_schema.Column`
objects. If omitted, all column expressions evaluated on the server
are added to the returning list.
.. versionadded:: 0.9.0
.. seealso::
:meth:`.UpdateBase.returning`
:attr:`_engine.ResultProxy.returned_defaults`
"""
if self._returning:
raise exc.InvalidRequestError(
"RETURNING is already configured on this statement"
)
self._return_defaults = cols or True
class Insert(ValuesBase):
"""Represent an INSERT construct.
The :class:`_expression.Insert` object is created using the
:func:`_expression.insert()` function.
.. seealso::
:ref:`coretutorial_insert_expressions`
"""
__visit_name__ = "insert"
_supports_multi_parameters = True
def __init__(
self,
table,
values=None,
inline=False,
bind=None,
prefixes=None,
returning=None,
return_defaults=False,
**dialect_kw
):
"""Construct an :class:`_expression.Insert` object.
Similar functionality is available via the
:meth:`_expression.TableClause.insert` method on
:class:`_schema.Table`.
:param table: :class:`_expression.TableClause`
which is the subject of the
insert.
:param values: collection of values to be inserted; see
:meth:`_expression.Insert.values`
for a description of allowed formats here.
Can be omitted entirely; a :class:`_expression.Insert` construct
will also dynamically render the VALUES clause at execution time
based on the parameters passed to :meth:`_engine.Connection.execute`.
:param 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
:class:`~sqlalchemy.schema.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.
.. seealso::
:ref:`coretutorial_insert_expressions` - SQL Expression Tutorial
:ref:`inserts_and_updates` - SQL Expression Tutorial
"""
ValuesBase.__init__(self, table, values, prefixes)
self._bind = bind
self.select = self.select_names = None
self.include_insert_from_select_defaults = False
self.inline = inline
self._returning = returning
self._validate_dialect_kwargs(dialect_kw)
self._return_defaults = return_defaults
def get_children(self, **kwargs):
if self.select is not None:
return (self.select,)
else:
return ()
@_generative
def from_select(self, names, select, include_defaults=True):
"""Return a new :class:`_expression.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)
:param names: a sequence of string column names or
:class:`_schema.Column`
objects representing the target columns.
:param select: a :func:`_expression.select` construct,
:class:`_expression.FromClause`
or other construct which resolves into a
:class:`_expression.FromClause`,
such as an ORM :class:`_query.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.
:param include_defaults: if True, non-server default values and
SQL expressions as specified on :class:`_schema.Column` objects
(as documented in :ref:`metadata_defaults_toplevel`) 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**.
.. versionadded:: 1.0.0 - :meth:`_expression.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.
.. versionchanged:: 1.0.0 an INSERT that uses FROM SELECT
implies that the :paramref:`_expression.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
:attr:`_engine.ResultProxy.inserted_primary_key`
accessor does not apply.
"""
if self.parameters:
raise exc.InvalidRequestError(
"This construct already inserts value expressions"
)
self.parameters, self._has_multi_parameters = self._process_colparams(
{_column_as_key(n): Null() for n in names}
)
self.select_names = names
self.inline = True
self.include_insert_from_select_defaults = include_defaults
self.select = _interpret_as_select(select)
def _copy_internals(self, clone=_clone, **kw):
# TODO: coverage
self.parameters = self.parameters.copy()
if self.select is not None:
self.select = _clone(self.select)
class Update(ValuesBase):
"""Represent an Update construct.
The :class:`_expression.Update`
object is created using the :func:`update()`
function.
"""
__visit_name__ = "update"
def __init__(
self,
table,
whereclause=None,
values=None,
inline=False,
bind=None,
prefixes=None,
returning=None,
return_defaults=False,
preserve_parameter_order=False,
**dialect_kw
):
r"""Construct an :class:`_expression.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
:meth:`_expression.TableClause.update` method on
:class:`_schema.Table`::
stmt = users.update().\
where(users.c.id==5).\
values(name='user #5')
:param table: A :class:`_schema.Table`
object representing the database
table to be updated.
:param whereclause: Optional SQL expression describing the ``WHERE``
condition of the ``UPDATE`` statement; is equivalent to using the
more modern :meth:`~Update.where()` method to specify the ``WHERE``
clause.
:param 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
:meth:`_expression.Update.values` method to set the values of the
UPDATE statement.
:param inline:
if True, SQL defaults present on :class:`_schema.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
:meth:`_engine.ResultProxy.last_updated_params`.
:param preserve_parameter_order: if True, the update statement is
expected to receive parameters **only** via the
:meth:`_expression.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.
.. versionadded:: 1.0.10
.. seealso::
:ref:`updates_order_parameters` - full example of the
:paramref:`_expression.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 :class:`_schema.Column`
objects or their string identifiers (specifically the "key" of the
:class:`_schema.Column`, normally but not necessarily equivalent to
its "name"). Normally, the
:class:`_schema.Column` objects used here are expected to be
part of the target :class:`_schema.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 :class:`_schema.Column`,
a scalar-returning :func:`_expression.select` construct,
etc.
When combining :func:`_expression.select` constructs within the values
clause of an :func:`_expression.update` construct,
the subquery represented by the :func:`_expression.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()
)
.. seealso::
:ref:`inserts_and_updates` - SQL Expression
Language Tutorial
"""
self._preserve_parameter_order = preserve_parameter_order
ValuesBase.__init__(self, table, values, prefixes)
self._bind = bind
self._returning = returning
if whereclause is not None:
self._whereclause = _literal_as_text(whereclause)
else:
self._whereclause = None
self.inline = inline
self._validate_dialect_kwargs(dialect_kw)
self._return_defaults = return_defaults
def get_children(self, **kwargs):
if self._whereclause is not None:
return (self._whereclause,)
else:
return ()
def _copy_internals(self, clone=_clone, **kw):
# TODO: coverage
self._whereclause = clone(self._whereclause, **kw)
self.parameters = self.parameters.copy()
@_generative
def where(self, 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 :meth:`_dml.Update.where` and :meth:`_dml.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.
.. seealso::
:ref:`tutorial_1x_correlated_updates`
:ref:`multi_table_updates`
:ref:`multi_table_deletes`
"""
if self._whereclause is not None:
self._whereclause = and_(
self._whereclause, _literal_as_text(whereclause)
)
else:
self._whereclause = _literal_as_text(whereclause)
@property
def _extra_froms(self):
froms = []
all_tables = list(sql_util.tables_from_leftmost(self.table))
seen = {all_tables[0]}
if self._whereclause is not None:
for item in _from_objects(self._whereclause):
if not seen.intersection(item._cloned_set):
froms.append(item)
seen.update(item._cloned_set)
froms.extend(all_tables[1:])
return froms
class Delete(UpdateBase):
"""Represent a DELETE construct.
The :class:`_expression.Delete`
object is created using the :func:`delete()`
function.
"""
__visit_name__ = "delete"
def __init__(
self,
table,
whereclause=None,
bind=None,
returning=None,
prefixes=None,
**dialect_kw
):
r"""Construct :class:`_expression.Delete` object.
Similar functionality is available via the
:meth:`_expression.TableClause.delete` method on
:class:`_schema.Table`.
:param table: The table to delete rows from.
:param whereclause: Optional SQL expression describing the ``WHERE``
condition of the ``DELETE`` statement; is equivalent to using the
more modern :meth:`~Delete.where()` method to specify the ``WHERE``
clause.
.. seealso::
:ref:`deletes` - SQL Expression Tutorial
"""
self._bind = bind
self.table = _interpret_as_from(table)
self._returning = returning
if prefixes:
self._setup_prefixes(prefixes)
if whereclause is not None:
self._whereclause = _literal_as_text(whereclause)
else:
self._whereclause = None
self._validate_dialect_kwargs(dialect_kw)
def get_children(self, **kwargs):
if self._whereclause is not None:
return (self._whereclause,)
else:
return ()
@_generative
def where(self, whereclause):
"""Add the given WHERE clause to a newly returned delete construct.
Both :meth:`_dml.Update.where` and :meth:`_dml.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.
.. seealso::
:ref:`tutorial_1x_correlated_updates`
:ref:`multi_table_updates`
:ref:`multi_table_deletes`
"""
if self._whereclause is not None:
self._whereclause = and_(
self._whereclause, _literal_as_text(whereclause)
)
else:
self._whereclause = _literal_as_text(whereclause)
@property
def _extra_froms(self):
froms = []
seen = {self.table}
if self._whereclause is not None:
for item in _from_objects(self._whereclause):
if not seen.intersection(item._cloned_set):
froms.append(item)
seen.update(item._cloned_set)
return froms
def _copy_internals(self, clone=_clone, **kw):
# TODO: coverage
self._whereclause = clone(self._whereclause, **kw)