sql - 如何从表中删除两个不同表中不相等的记录

Question

我有 A、B、C 是三个不同的表，我需要从 A 表中删除在 B 和 C 表中都不存在的记录。

样本：

 delete from A 
 where name NOT IN ( select name from B inner join C);

Answer 1

我喜欢对这样的东西使用左连接。我首先创建一个这样的选择语句：

SELECT  *
FROM    TableA AS a 
        LEFT OUTER JOIN TableB AS b ON a.Name = b.Name
        LEFT OUTER JOIN TableC AS c ON a.Name = c.Name
WHERE  b.Name IS NULL
       AND c.NAME IS NULL

然后我转换成这样的 DELETE 语句：

DELETE  a 
FROM    TableA AS a 
        LEFT OUTER JOIN TableB AS b ON a.Name = b.Name
        LEFT OUTER JOIN TableC AS c ON a.Name = c.Name
WHERE  b.Name IS NULL
       AND c.NAME IS NULL