mysql的三中查询找出不重复的记录

Else , 2010/04/24 00:04 , 代码片段，演示也有 , Comments(0) , Reads(457) , Via Original

Quotation

#--从新闻表中找出有记录的新闻分类
select (select catname from cuku_newscat where cuku_newscat.catname=cuku_news.catname) as catname from cuku_news group by cuku_news.catname

Quotation

#--从新闻分类表中找出有记录的新闻分类

select (select catname from cuku_news where cuku_newscat.catname=cuku_news.catname limit 1 ) as catname
from cuku_newscat
where catname is not null group by cuku_newscat.catname

Quotation

#--交差查询新闻表与新闻分类表

select cuku_newscat.catname from cuku_newscat ,cuku_news where cuku_newscat.catname=cuku_news.catname group by cuku_news.catname