带有空值列的MySQL查询

Question

我有这个问题：

 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))

列'perm'（权限）是一个int值，可以是1,2,3，ecc等值。 或空值。 我想要一个像这样的查询：

 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，我希望从查询中删除perm = 3的记录。

我认为我可以用这种方式检索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....

任何想法？

谢谢

Answer 1

尝试这个

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