在进行一张表进行groupby后获取最大id和最小id数据的sql语句

在进行一张表进行groupby后获取最大id和最小id数据的sql语句；

方法一：变量

select result.* from (  

         select heyf_tmp.*,@rownum:=@rownum+1 as rownum, 

               if(@pdept=heyf_tmp.id,@rank:=@rank+1,@rank:=1) as rank, 

               @pdept:=heyf_tmp.id as id1 

from ( 

select distinct bpt.id, spi.userid,spi.startTime,spi.endTime,spi.orgId,spi.projectCode,

spi.endTime finishtime,1 as result,IFNULL(bpt.planName,'日常巡查') planName,

su.nickname nickname,bwp.`name` projectCodeName from bus_patrol_info spi

  left join bus_patrol_task bpt on spi.orgid=bpt.orgid and bpt.result=1 

  left join sys_user su on spi.userId = su.id

  left JOIN bus_water_project bwp on bwp.`code` = bpt.projectCode

  where 1=1

 AND spi.orgId = "372" and spi.userId = bpt.userId 

order by bpt.id,spi.startTime desc

) heyf_tmp , 

    (select @rownum :=0 , @pdept := null ,@rank:=0) a 

 ) result where rank=1

方法为： MAX(id)-》 GROUP_CONCAT(a.id)-》FIND_IN_SET

SELECT a.waterlevel,IFNULL(1/IFNULL(1/(max(flow)-min(flow)),0),0) flow,time FROM(

select AVG(waterlevel) waterlevel,flow,time from bus_waterregime 

GROUP BY  DATE_FORMAT(time,'%Y-%m-%d %H') UNION

SELECT 'NaAVG' waterlevel,flow,time FROM bus_waterregime b where 

FIND_IN_SET(b.id,(SELECT GROUP_CONCAT(a.id) id FROM(

select MAX(id) id from bus_waterregime GROUP BY  DATE_FORMAT(time,'%Y-%m-%d %H'))a))

)a GROUP BY DATE_FORMAT(time,'%Y-%m-%d %H')

在公司有限的数据中两者的查询时间差不多，如有兴趣者可以一试两者的性能如何