Given the following declarative schema, how can I generate the UPDATE
statement? I am using MySQL
class A(Base):
__tablename__ = 'a'
id = Column(Integer, primary_key=True)
str = Column(String(16), nullable=False)
bs = relationship(B)
class B(Base):
__tablename__ = 'b'
id = Column(Integer, primary_key=True)
a_id = Column(Integer, ForeignKey(A.id), nullable=False)
typ = Column(Enum('1', '2'), nullable=False)
str = Column(String(16), nullable=False)
__table_args__ = ( UniqueConstraint(a_id, typ), )
UPDATE a
INNER JOIN b ON b.a_id = a.id
SET a.str = CONCAT(a.str, b.str)
WHERE b.typ = '2';
I have tried
session.query(A).join(B).filter(B.typ == '2').update({ 'str':
func.concat(A.str, B.str) }, synchonize_session=False)
but this raises an exception
s.execute(update(A).join(B, b.a_id == A.id).where(B.typ ==
'2').values(str=func.concat(A.str, B.str)))
does not work because join is not a member of Update
How can I achieve this? It would be especially nice if I could use the
session to do so rather than raw sql expression
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http://www.sqlalchemy.org/
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