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Classe « Select »

Méthode sqlalchemy.Select.join

Signature de la méthode join

def join(self, target: '_JoinTargetArgument', onclause: 'Optional[_OnClauseArgument]' = None, *, isouter: 'bool' = False, full: 'bool' = False) -> 'Self' 

Description

help(Select.join)

Create a SQL JOIN against this :class:`_expression.Select`
object's criterion
and apply generatively, returning the newly resulting
:class:`_expression.Select`.

E.g.::

    stmt = select(user_table).join(
        address_table, user_table.c.id == address_table.c.user_id
    )

The above statement generates SQL similar to:

.. sourcecode:: sql

    SELECT user.id, user.name
    FROM user
    JOIN address ON user.id = address.user_id

.. versionchanged:: 1.4 :meth:`_expression.Select.join` now creates
   a :class:`_sql.Join` object between a :class:`_sql.FromClause`
   source that is within the FROM clause of the existing SELECT,
   and a given target :class:`_sql.FromClause`, and then adds
   this :class:`_sql.Join` to the FROM clause of the newly generated
   SELECT statement.    This is completely reworked from the behavior
   in 1.3, which would instead create a subquery of the entire
   :class:`_expression.Select` and then join that subquery to the
   target.

   This is a **backwards incompatible change** as the previous behavior
   was mostly useless, producing an unnamed subquery rejected by
   most databases in any case.   The new behavior is modeled after
   that of the very successful :meth:`_orm.Query.join` method in the
   ORM, in order to support the functionality of :class:`_orm.Query`
   being available by using a :class:`_sql.Select` object with an
   :class:`_orm.Session`.

   See the notes for this change at :ref:`change_select_join`.


:param target: target table to join towards

:param onclause: ON clause of the join.  If omitted, an ON clause
 is generated automatically based on the :class:`_schema.ForeignKey`
 linkages between the two tables, if one can be unambiguously
 determined, otherwise an error is raised.

:param isouter: if True, generate LEFT OUTER join.  Same as
 :meth:`_expression.Select.outerjoin`.

:param full: if True, generate FULL OUTER join.

.. seealso::

    :ref:`tutorial_select_join` - in the :doc:`/tutorial/index`

    :ref:`orm_queryguide_joins` - in the :ref:`queryguide_toplevel`

    :meth:`_expression.Select.join_from`

    :meth:`_expression.Select.outerjoin`

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