sql - 同一列中最大日期和最小日期之间的值之间的差异？

Question

需要有关 MS SQL 查询的帮助。我需要显示同一列中两个值之间的差异，其中数据位于最大日期和最小日期之间。例如，如果我有下表:

see details behind the image

location|   date        |amount
------- |   -------     |-------
1000    |   2016-01-01  |400
1000    |   2016-01-04  |600    
1000    |   2016-01-05  |650
1000    |   2016-01-06  |820
1000    |   2016-01-18  |850
1000    |   2016-01-22  |900
1000    |   2016-01-28  |910
1000    |   2016-01-31  |950
2000    |   2016-01-07  |100
2000    |   2016-01-13  |150
2000    |   2016-01-15  |260
2000    |   2016-01-20  |330

输出应如下所示:

location|   difference
------- |   -------
1000    |   550
2000    |   230

提前致谢。

Answer 1

您可以如下:

SELECT
   location,
   MAX(Amount) - MIN(Amount) difference
FROM
  Tbl
GROUP BY
  location

已更新

SELECT
    T.location,
    Maxv.Amount - Minv.Amount as difference
FROM
(
    SELECT
       location,
       MIN(date) MinDate,
       MAX(date) MaxDate
    FROM
      Tbl A 
    GROUP BY
      location
) T INNER JOIN 
Tbl Minv ON T.MinDate = Minv.date AND T.location = Minv.location INNER JOIN 
Tbl Maxv ON T.MaxDate= Maxv.date AND T.location = Maxv.location