mysql的联表删除

联表删除：

1、从数据表t1 中把那些id值在数据表t2 里有匹配的记录全删除掉

DELETE t1 FROM t1,t2 WHERE t1.id=t2.id    或DELETE  FROM t1 USING t1,t2 WHERE t1.id=t2.id

2、从数据表t1里在数据表t2里没有匹配的记录查找出来并删除掉

DELETE t1 FROM t1 LEFT JOIN T2 ON t1.id=t2.id WHERE t2.id IS NULL 或

DELETE  FROM t1,USING t1 LEFT JOIN T2 ON t1.id=t2.id WHERE t2.id IS NULL

3、从两个表中找出相同记录的数据并把两个表中的数据都删除掉

DELETE t1,t2 from t1 LEFT JOIN t2 ON t1.id=t2.id WHERE t1.id=25