Question

有没有办法从MySQL join Query中删除匹配的行。实际上我有两个表，我存储了pub_id，而post_id在两个表中都是常见的。当我查询table1中的所有匹配行时，我想要一个结果，并且不应该列出table2，并且应该仅列出不匹配的行。

Answer 1

查询仅存在于两个表之一中的返回行：

SELECT *
FROM Table1 t1
WHERE NOT EXISTS (Select 1 from Table2 t2 
                 Where t1.pub_id = t2.pub_id
                AND t1.post_Id = t2.post_id)
UNION ALL
SELECT *
FROM Table2 t1
WHERE NOT EXISTS (Select 1 from Table1 t2 
                 Where t1.pub_id = t2.pub_id
                AND t1.post_Id = t2.post_id)

Answer 2

你需要这样的东西：

    SELECT * FROM tablea AS a
   RIGHT  JOIN tableb AS o ON a.id = o.id WHERE a.pub_id IS NULL and a.post_id is null 
UNION    
SELECT * FROM tablea AS a
   LEFT  JOIN tableb AS o ON a.id = o.id WHERE o.pub_id IS NULL and o.post_id is null

如何从mysql中删除匹配的行Join Result并显示不匹配的行？

2 个答案: