sql - 在一列中减去并在其他列中添加的最简单方法

Question

基本上我正在尝试将存在从一个寄存器移动到另一个寄存器，从原点减去并将其添加到命运中。我有一张这样的“股票”表：

国家城市价值

AA      01   500
AA      02   400
BB      01   300
CC      01   100
CC      02  1000
CC      03  2000

我收到了一份结构如下的“运动”文件：
数量 originCountry originCity endCountry endCity

10      AA             01         CC         01
20      AA             01         BB         02
50      BB             01         CC         03

有没有办法在不创建两个规范化表和几个查询的情况下做到这一点。

编辑

答案应该是这样的：

数量 originCountry originCity endCountry endCity

AA      01   470
AA      02   400
BB      01   250
CC      01   110
CC      02  1020
CC      03  2050

负数和业务规则不相关

Answer 1

试试这个（isnull 用于 tsql）：

SELECT country, city, value - isnull(p, 0) + isnull(m, 0) as q
FROM Stocks AS s
LEFT JOIN (SELECT originCountry, originCity, Sum(quantity) m FROM movements GROUP BY originCountry, originCity) AS mm 
  ON originCountry = s.country AND originCity = s.city
LEFT JOIN (SELECT endCountry, endCity, Sum(quantity) p FROM movements GROUP BY endCountry, endCity) AS mp ON
  ON endCountry = s.country AND endCity = s.city

对于MS ACCESS（下次添加标签......）：
这应该可以工作：

SELECT country, city, value - Nz(p, 0) + Nz(m, 0) as q
FROM ((Stocks AS s
LEFT JOIN (SELECT originCountry, originCity, Sum(quantity) m FROM movements GROUP BY originCountry, originCity) AS mm 
  ON (originCountry = s.country AND originCity = s.city))
LEFT JOIN (SELECT endCountry, endCity, Sum(quantity) p FROM movements GROUP BY endCountry, endCity) AS mp ON
  ON (endCountry = s.country AND endCity = s.city))

或者这个（（如果你得到错误然后使用 DSum 函数）：

SELECT country, city, value 
  - Nz((
    SELECT Sum(quantity) m 
    FROM movements 
    WHERE originCountry = s.country AND originCity = s.city
  ), 0) + Nz((
    SELECT Sum(quantity) p 
    FROM movements 
    WHERE endCountry = s.country AND endCity = s.city
  ), 0) as q
FROM Stocks AS s