问题:
假设x表中的数据为
y表中的数据为
如何把x表里面字段a,b和y表里面a,b相同的删除?
尝试:
DELETE FROM x WHERE a IN (SELECT a FROM y) AND b IN (SELECT b FROM y);
这样做是错误的,把x表中所有数据都删除了
解决办法:
DELETE FROM x WHERE (a,b) IN (SELECT a,b FROM y);
假设x表中的数据为
y表中的数据为
如何把x表里面字段a,b和y表里面a,b相同的删除?
DELETE FROM x WHERE a IN (SELECT a FROM y) AND b IN (SELECT b FROM y);
这样做是错误的,把x表中所有数据都删除了
DELETE FROM x WHERE (a,b) IN (SELECT a,b FROM y);