我的这条查询语句有什么问题吗?为什么一运行,机器就卡死了!N久查询不出结果呀!求高手指点呀!
记录数并不多呀!也就1W多条呀!select imageid,path,keywords,viewcount,filename,created from images where imageid in(select max(imageid) FROM images group by keywords ) and categoryid<=4 order by viewcount desc LIMIT 10
实在想不出是什么原因!
from images A
where categoryid<=4 and not exists (select 1 from images B where A.keywords=B.keywords and A.imageid<B.imageid)
order by viewcount desc
LIMIT 10
[征集]分组取最大N条记录方法征集,及散分....
inner join (select max(imageid) as ma FROM images group by keywords ) b
on a.imageid=b.ma and categoryid<=4
order by viewcount desc LIMIT 10