Question

我有这样的表：

PRODUCTID      REORDER_QTY      TYPE      ADJUST_TYPE  
-------------  ---------------  --------  -----------------
         4343             2.00  Transfer  ADD              
         4730             2.00  Transfer  ADD              
         4730             2.00  Transfer  ADD              
         4730             1.00  Transfer  DEDUCT           
         3643            20.00  Transfer  ADD              
         3643             3.00  Transfer  DEDUCT

如何通过 PRODUCTID 以及 ADJUST_TYPE 编写一个sql来累计 REORDER_QTY ，之后通过总和得到它的余额 ADD 并减去总和 DEDUCT

我想要的示例sql结果输出：

PRODUCTID        TYPE                   Total_Balance
-------------    ----------             ---------------
4730             Transfer               ((SUM the REORDER_QTY by ADD) - (SUM the REORDER_QTY by DEDUCT))
3643             Transfer               ((SUM the REORDER_QTY by ADD) - (SUM the  REORDER_QTY by DEDUCT))
4343             Transfer               ((SUM the REORDER_QTY by ADD) - (SUM the  REORDER_QTY by DEDUCT))

任何帮助都会很棒，谢谢

Answer 1

您只想要条件聚合：

select productid, type,
       sum(case when adjust_type = 'ADD' then reorder_qty
                when adjust_type = 'DEDUCT' then - reorder_qty
                else 0
           end) as total_balance
from atable
group by productid, type;

Answer 2

因为这是mysql，所以你可以这样做：

select
    productid,
    sum((2 * (adjust_type = 'ADD') - 1) * reorder_qty) as total_balance
from mytable
group by productid

这是有效的，因为在mysql中，布尔条件为true生成1的结果，为false生成0，因此(2 * (adjust_type = 'ADD') - 1)为1和ADD生成-1，否则，使算术更简单。

MYSQL：SUM与多个组

2 个答案: