SQLAlchemy:如何使用联接删除 [英] SQLAlchemy: How to Delete with join

问题描述

我在使用SQLAlchemy进行此类操作时遇到了麻烦:

I have trouble doing such thing bottom with SQLAlchemy:

DELETE a FROM a INNER JOIN b ON b.`aId` = a.`Id` WHERE `b`.`xxx` = ?;

作为此处的帖子: SQLAlchemy:使用以下命令创建删除查询在MySQL上自连接

我很难通过join在SQLAlchemy中进行删除.

I've got it's hard to do delete in SQLAlchemy with join.

所以我现在是这样的:

session.execute('DELETE a FROM a INNER JOIN b ON b.`aId` = a.`Id` WHERE `b`.`xxx` = %d;'%xxx)

但这让我很烦，例如:SQL注入之类的东西.

But it just annoy me a lot like about: SQL Injection thing, etc..

有什么方法可以使用SQLAlchemy在这里解决问题?谢谢！

Is there any way using SQLAlchemy to solve the problem here? Thanks!

推荐答案

某些方言的多表删除(在编写Postgresql，MySQL和Microsoft SQL Server时):

SQLAlchemy 1.2 and up support multi table deletes for some dialects (at the time of writing Postgresql, MySQL and Microsoft SQL Server):

In [18]: a = table('a', column('x'))

In [19]: b = table('b', column('x'))

In [20]: c = table('c', column('x'), column('y'))

In [21]: a.delete().\
    ...:     where(a.c.x == b.c.x).\
    ...:     where(b.c.x == c.c.x).\
    ...:     where(c.c.y == 1)
Out[21]: <sqlalchemy.sql.dml.Delete object at 0x7f3577d89160>

In [22]: print(_.compile(dialect=mysql.dialect()))
DELETE FROM a USING a, b, c WHERE a.x = b.x AND b.x = c.x AND c.y = %s

，并使用Session和声明性语言:

and the same using a Session and Declarative:

In [2]: class Foo(Base):
   ...:     __tablename__ = 'foo'
   ...:     id = Column(Integer, primary_key=True)

In [3]: class Bar(Base):
   ...:     __tablename__ = 'bar'
   ...:     id = Column(Integer, primary_key=True)
   ...:     foo_id = Column(ForeignKey(Foo.id))
   ...:     

In [4]: class Baz(Base):
   ...:     __tablename__ = 'baz'
   ...:     id = Column(Integer, primary_key=True)
   ...:     bar_id = Column(ForeignKey(Bar.id))
   ...:     val = Column(Integer)
   ...:     

In [5]: session.query(Foo).\
   ...:     filter(Foo.id == Bar.foo_id,
   ...:            Bar.id == Baz.bar_id,
   ...:            Baz.val == 1).\
   ...:     delete(synchronize_session=False)
   ...:            

会发出

DELETE FROM foo USING foo, bar, baz
WHERE foo.id = bar.foo_id AND bar.id = baz.bar_id AND baz.val = %(val_1)s

这篇关于SQLAlchemy:如何使用联接删除的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！