MYSQL操作之求百分比,過濾重複超過5條的數據，保留5條內的信息

mysql 百分比保留小數點後兩位：
concat(TRUNCATE(SUM(ag.net_amount)/SUM(ag.net_amount)* 100, 2),’%’) as winning

mysql 操作保留小數點後兩位：
COUNT(IF(IFNULL(mg1.amount,-mg.amount)>0,mg1.amount,NULL))/COUNT(mg.amount) as value

按最新時間addtime ，過濾phoneid重複超過5條的信息，保留5條內的信息

select phoneid,media_id,metatype,title,addtime,new_rank as rank from (select phoneid,media_id,metatype,title,addtime, IF(@tmp=phoneid,@rank:=@rank + 1,@rank:=1) as new_rank, @tmp:=phoneid as tmp from phone_playhistory order by phoneid,addtime desc)b where new_rank < 6;