Question

假设我有一个像

这样的表

Room    Day People  Theme
A   14/05/2014  12  Water
A   12/05/2014  245 Mathematics
A   05/04/2014  215 Nature
B   10/09/2013  252 Water
B   10/05/2012  221 Cinema
B   05/10/2011  215 Cinema
C   10/10/2013  224 Mathematics
C   02/06/2013  245 Cooking
C   05/03/2013  15  Cooking

并希望获得一个表格，其中包含每个房间A，B和C的行，以及说明其使用日期，参加人数和会议主题的列。

结果将是一个表格：

Room    Day People  Theme
A   14/05/2014  12  Water
B   10/09/2013  252 Water
C   10/10/2013  224 Mathematics

这只是一个例子，真实的表包含很多行。

是否有快速SQL代码可以在不说明所有房间的情况下获取该代码？

Answer 1

您可以尝试此查询：

SELECT ROOM, MAX(DAY), PEOPLE, THEME 
FROM TABLE_NAME
GROUP BY ROOM, PEOPLE, THEME;

Answer 2

获取每间客房的最长日期。然后加入你的表格以获得完整的记录：

select rooms.*
from rooms
join
(
  select room, max(day) as max_day
  from rooms
  group by room
) last_used on last_used.room = rooms.room and last_used.max_day = room.day;

Answer 3

With CTE As (
Select room,
        day,
        people,
        theme,
        Row_Number() Over(Partition By Room Order By Day Desc) RowNumber
        )
        Select * From CTE Where RowNumber = 1

需要SQL查询帮助 - 每个行组具有最大日期值的故事

3 个答案: