左联接的结果为空

Question

我有一个奇怪的结果来自mysql查询：

如果我用

SELECT cbe.id, cbe.user_id, cbe_profile_gender ,bud.status,cbe.avatar
FROM findme as cbe 
LEFT JOIN findme_buddylist as bud ON cbe.user_id = bud.userid 
WHERE cbe.user_id<>2122 
AND cbe.avatar != "" 
AND bud.status != "2"

我没有结果，因为表ade39_findme_buddylist为空

但是如果我删除行：

AND bud.status != "2"

我得到的结果表明bud.status = NULL

怎么了？

谢谢 ！！！

Answer 1

LEFT JOIN 第二个表的条件应该在in子句中：

SELECT cbe.id, cbe.user_id, cbe_profile_gender ,bud.status,cbe.avatar
FROM ade39_findme cbe LEFT JOIN
     ade39_findme_buddylist bud
     ON cbe.user_id = bud.userid and bud.status <> 2
WHERE cbe.user_id <> 2122 AND cbe.avatar <> '';