Question

我在mySQL中有一个表，其中包含以下列：

CUSTOMER_CODE | TRANS_TYPE | TRANS_VALUE

TRANS_TYPE可以是“DRINV”（销售）或“DRCDT”（信用卡）。

我想获得每位客户的总销售额，所以到目前为止我的查询是：

SELECT CUSTOMER_CODE, SUM(TRANS_VALUE) as SALES FROM DR_TRANS GROUP BY CUSTOMER_CODE

问题在于这是销售和信用额的总和，而不是给予销售额减去信用额。我希望结果是

SUM(TRANS_VALUE) where TRANS_TYPE = "DRINV" - SUM(TRANS_VALUE) where TRANS_TYPE = "DRCDT".

是否可以在SQL查询中执行此操作？

Answer 1

select customer_code,
       sum(case
             when trans_type = 'DRINV' then
              trans_value
             else
              -trans_value
           end) as net_sales
  from dr_trans
 group by customer_code

Answer 2

是的，有可能。使用CASE子句：

SELECT CUSTOMER_CODE,
SUM(CASE WHEN TRANS_TYPE = 'DRINV' THEN TRANS_VALUE ELSE (- TRANS_VALUE) END ) as SALES
FROM DR_TRANS GROUP BY CUSTOMER_CODE

SQL - 某些行的总和，减去其他行的总和

2 个答案: