Question

我的表有列类型（0或1），金额（int）

我需要查询什么返回2个参数：type = 1的总和金额和type = 0的总金额

2个查询：

SELECT SUM(amount) AS income FROM table WHERE type = 0;

SELECT SUM(amount) AS expense FROM table WHERE type = 1;

但我可以仅使用1个查询返回这些参数吗？

Answer 1

SELECT SUM(amount), IF(type=0, 'income', 'expense') AS type
FROM table
GROUP BY type

Answer 2

SELECT sum(case when type = 0 
           then amount
           else 0 
           end) AS income,
       sum(case when type = 1 
           then amount
           else 0
           end) AS expense
FROM table

在1个查询中：2个结果，使用2个条件

2 个答案:

Demo