python - 包含空值列的 MySQL 查询

Question

我有这个查询:

 user = self.db.query("SELECT DISTINCT u.id, u.name, n.network_id, n.perm \ 
FROM users as u LEFT OUTER JOIN nets_permissions as n \ 
ON u.id = n.user_id WHERE u.id!=%s", int(usr_id))

“perm”(权限)列是一个 int 值，可以是 1、2、3、ecc 等值。或空值。我想要这样的查询:

 user = self.db.query("SELECT DISTINCT u.id, u.name, n.network_id, n.perm \
FROM users as u LEFT OUTER JOIN nets_permissions as n \
ON u.id = n.user_id WHERE u.id!=%s" AND n.perm!=3, int(usr_id))

所以，我想从查询中删除 perm=3 的记录。

我认为我可以通过这种方式检索 perm=3 的用户的 id:

self.lock_tables("read", ['nets_permissions'])
        admin = self.db.query("SELECT user_id FROM nets_permissions \
                               WHERE network_id=%s AND perm=3", nid)
        self.unlock_tables()

然后我就可以写了

 self.lock_tables("read", ['users as u', 'nets_permissions as n'])
   user = self.db.query("SELECT DISTINCT u.id, u.name, n.network_id, n.perm \
FROM users as u LEFT OUTER JOIN nets_permissions as n \
ON u.id = n.user_id WHERE u.id!=%s AND u.id!=%s", int(usr_id), int(admin))
            self.unlock_tables() 

但这不起作用......

有什么想法吗？

谢谢

Answer 1

试试这个

SELECT DISTINCT u.id, u.name, n.network_id, n.perm 
FROM users as u 
LEFT OUTER JOIN nets_permissions as n 
ON u.id = n.user_id 
AND n.perm<> 3 
WHERE u.id!=%s