Module « sqlalchemy »

Fonction update - module sqlalchemy

Signature de la fonction update

def update(table, whereclause=None, values=None, inline=False, bind=None, prefixes=None, returning=None, return_defaults=False, preserve_parameter_order=False, **dialect_kw) 

Description

update.__doc__

Construct an :class:`_expression.Update` object.

        E.g.::

            from sqlalchemy import update

            stmt = (
                update(user_table).
                where(user_table.c.id == 5).
                values(name='user #5')
            )

        Similar functionality is available via the
        :meth:`_expression.TableClause.update` method on
        :class:`_schema.Table`.

        .. seealso::

            :ref:`inserts_and_updates` - in the
            :ref:`1.x tutorial <sqlexpression_toplevel>`

            :ref:`tutorial_core_update_delete` - in the :ref:`unified_tutorial`



        :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.

         .. deprecated:: 1.4 The :paramref:`_expression.update.whereclause` parameter will be removed in SQLAlchemy 2.0.  Please refer to the :meth:`_expression.Update.where` method.



        :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.

          .. deprecated:: 1.4 The :paramref:`_expression.update.values` parameter will be removed in SQLAlchemy 2.0.  Please refer to the :meth:`_expression.Update.values` method.



          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.CursorResult.last_updated_params`.

          .. deprecated:: 1.4 The :paramref:`_expression.update.inline` parameter will be removed in SQLAlchemy 2.0.  Please use the :meth:`_expression.Update.inline` method.



        :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.

          .. deprecated:: 1.4 The :paramref:`_expression.update.preserve_parameter_order` parameter will be removed in SQLAlchemy 2.0.   Use the :meth:`_expression.Update.ordered_values` method with a list of tuples. 



          .. versionadded:: 1.0.10

          .. seealso::

            :ref:`updates_order_parameters` - illustrates the
            :meth:`_expression.Update.ordered_values` method.

        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).\
                            scalar_subquery()
                )

        .. seealso::

            :ref:`inserts_and_updates` - SQL Expression
            Language Tutorial