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Classe « Query »

Méthode sqlalchemy.orm.Query.union

Signature de la méthode union

def union(self, *q: 'Query[Any]') -> 'Self' 

Description

help(Query.union)

Produce a UNION of this Query against one or more queries.

e.g.::

    q1 = sess.query(SomeClass).filter(SomeClass.foo == "bar")
    q2 = sess.query(SomeClass).filter(SomeClass.bar == "foo")

    q3 = q1.union(q2)

The method accepts multiple Query objects so as to control
the level of nesting.  A series of ``union()`` calls such as::

    x.union(y).union(z).all()

will nest on each ``union()``, and produces:

.. sourcecode:: sql

    SELECT * FROM (SELECT * FROM (SELECT * FROM X UNION
                    SELECT * FROM y) UNION SELECT * FROM Z)

Whereas::

    x.union(y, z).all()

produces:

.. sourcecode:: sql

    SELECT * FROM (SELECT * FROM X UNION SELECT * FROM y UNION
                    SELECT * FROM Z)

Note that many database backends do not allow ORDER BY to
be rendered on a query called within UNION, EXCEPT, etc.
To disable all ORDER BY clauses including those configured
on mappers, issue ``query.order_by(None)`` - the resulting
:class:`_query.Query` object will not render ORDER BY within
its SELECT statement.

.. seealso::

    :meth:`_sql.Select.union` - v2 equivalent method.

Vous êtes un professionnel et vous avez besoin d'une formation ? Programmation Python
Les fondamentaux Voir le programme détaillé