difference between "on" and "where" when using left/right join query
摘要：
I used to put the where-condiction in the "on" substatement in a join query,wishing that can help reducing the join count and improving the performence.But totally i was wrong.It seems the on-condiction is not like the where-condiction in a left/right join query. For example, there are two 阅读全文
posted @ 2013-04-23 18:38 wyman25 阅读(192) 评论(0) 推荐(0) 编辑