如何从查询中获取有效数据

Question

这是我的结果。我只想选择第一个＆＃39; in＆＃39;状态和第一个＆＃39;最后一个＆＃39;每个日期的状态，但我无法做到。

Answer 1

我认为使用窗口功能可以帮助您：

select * from 
(select 
 rownum = row_number() 
     over (partition by staffid, 
       convert(varchar(10), attendDate, 126), 
       status 
       order by attendDate)
 , * 
 from test
 ) x 
 where rownum = 1
 order by staffid, attendDate

每天选择最后结帐也是明智的：

select * from 
(select 
 rownum = row_number() 
     over (partition by staffid, 
       convert(varchar(10), attendDate, 126), 
       status 
       order by 
         case when status = 'in' then attendDate else 0 end,
         case when status = 'out' then attendDate else 0 end desc
       )
 , * 
 from test
 ) x 
 where rownum = 1
 order by staffid, attendDate