使用 SQL 在基于加法或减法条件的新列中计算总计 运行

Question

我正在尝试根据帐户和日期的另一列中的值 plus/minus 计算总计 运行。

示例

Data 
ID     Account  Date         Operation         Qty              Running_Total 
1       A       01/01/2018       plus           10              10
2       A       01/02/2018       plus           20              30 
3       A       01/03/2018       minus           5              20
4       A       01/03/2018       minus           5              20
5       A       01/04/2018       plus           30              50
6       B       01/01/2018       plus           15              15

总数

Code: 
select ID, Date, Operation, Total, 
              case when Operation = 'Use Table B' then TableB.RunningTotalQty 
              else
              SUM( case when Operation = 'plus' then  Qty 
                   else case when Operation = 'minus' then -Qty end) 
              OVER (PARTITION BY Account ORDER BY Date)  end
            From TableA A left Join TableB B 
on A.ID = B.ID ...

Answer 1

这回答了问题的原始版本。

case 进入 sum():

select ID, Date, Operation, Total, 
       sum(case when Operation = 'plus' then qty else - qty end) over
           (partition by Account order by Date) as Running_Total
From TableA  ;

这假设只有两个操作。如果你有更多：

select ID, Date, Operation, Total, 
       sum(case when Operation = 'plus' then qty
                then Operation = 'minus' then - qty
                else 0
           end) over
           (partition by Account order by Date) as Running_Total
From TableA  ;