mysql - 在 1 个查询中：2 个结果，使用 2 个条件

Question

我有列类型（0 或 1）、数量（int）的表

我需要查询返回 2 个参数的内容：类型 = 1 的总金额和类型 = 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;

但是我可以只使用 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

演示