MySQL左联多表查询where条件写法示例

来源：动视网责编：小采时间：2020-11-09 21:01:21

MySQL左联多表查询where条件写法示例

MySQL左联多表查询where条件写法示例: 代码如下: select * from _test a left join _test b on a.id=b.id where a.level='20' and a.month='04' and b.level='20' and b.month='03'; select a.*,b.* from (select * from _test where

推荐度：

点击下载本文 文档为doc格式

导读MySQL左联多表查询where条件写法示例: 代码如下: select * from _test a left join _test b on a.id=b.id where a.level='20' and a.month='04' and b.level='20' and b.month='03'; select a.*,b.* from (select * from _test where

代码如下:
select * from _test a left join _test b on a.id=b.id where a.level='20' and a.month='04' and b.level='20' and b.month='03';

select a.*,b.* from (select * from _test where level='20' and month='04') as a left join (select * from _test where level='20' and month='03') as b on a.id=b.id;

这两条语句结果是不同的，应该是left join的时候如果条件是多个表mysql会自动转成内联导致，第二条语句才能达到正确的目的(为了找到相差的两条数据)。