select result.* from (
 select heyf_tmp.*,@rownum:=@rownum+1,
 if(@pdept=heyf_tmp.group_no,@rank:=@rank+1,@rank:=1) as rank,
 @pdept:=heyf_tmp.group_no
 from ( 
 select * from commodity_package  order by detail_id asc 
 ) heyf_tmp ,(select @rownum :=0 , @pdept := null ,@rank:=0) a ) result 
where result.package_id = 4 and result.rank = 1
 ;