sql 分组后取第一条

chuangkou 窗口号 BH_HAO 排号，IS_CALL 是否叫号，TIME_CALL叫号时间，RIQI日期

求 ：按窗口号分组排序且只显示该窗口最新一个记录。

select BH_Hao as QueueNum,ChuangKou as WinId  from PD_ReCode awhere  not  exists

 (select *  from PD_ReCode b  where a.ChuangKou=b.ChuangKou and a.Time_Call<b.Time_Call  )
 and    IS_Call=1 and DATEDIFF(dd,RiQi,GETDATE())=0
 order by a.ChuangKou