Question

这是我的表

expiration_interval

我想将行的总和结果与（01,03,05）中的代码显示为借方，将（02,04,06）显示为贷方，所以结果看起来像这样

|id | code | amount |
----------------------
|1  |  01  | 500    | 
|2  |  02  | 2500   | 
|3  |  03  | 700    | 
|4  |  04  | 500    | 
|5  |  05  | 500    | 
|6  |  06  | 500    |

它怎么能这样做？提前谢谢：）

Answer 1

一种选择是使用conditional aggregation：

select 
    sum(case when code in ('01','03','05') then amount end) debit,
    sum(case when code in ('02','04','06') then amount end) credit
from yourtable

Answer 2

另一种变体，有时候条件聚合可能更好：

select sum(debit), sum(credit) from
(
select sum(amount) as debit, 0 as credit
from table where code in ('01','03','05')
union all
select 0, sum(amount)
from table where code in ('02','04','06')
) as q

实际性能取决于表结构/大小/索引，因此运行explain以确定哪种变体更可取

mysql - 从带有sum（）和where子句的表中选择

2 个答案: