delete 多表删除的使用

delete 多表删除的使用
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



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



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

注意此处的delete t1,t2 from 中的t1,t2不能是别名

如:

delete t1,t2 from table_name as t1 left join table2_name as t2 on t1.id=t2.id where table_name.id=25

在数据里面执行是错误的(MYSQL 版本不小于5.0在5.0中是可以的)

上述语句改写成

delete table_name,table2_name from table_name as t1 left join table2_name as t2 on t1.id=t2.id where table_name.id=25

在数据里面执行是错误的(MYSQL 版本小于5.0在5.0中是可以的)

附:上述语句运行的环境 MYSQL 4.0.2以上
posted @ 2009-03-20 00:08 貔貅 阅读(...) 评论(...) 编辑 收藏