MYSQL：在一个查询中计算按两个不同条件分组的列的SUM

Question

说我有这些示例数据的简化表结构：

id | duration_seconds (int) | is_billable (boolean)
1  | 100                    | false
2  | 500                    | true
3  | 100                    | false
4  | 150                    | true

是否可以通过单个查询获得类似结果？

total_duration | billable_duration | non_billable_duration
850            | 650               | 200

Answer 1

您可以使用条件聚合在一个查询中获得不同的总和：

SELECT SUM(duration_seconds ) AS total_duration,
       SUM(CASE WHEN is_billable THEN duration_seconds ELSE 0 END) AS billable_duration,
       SUM(CASE WHEN NOT is_billable THEN duration_seconds ELSE 0 END) AS non_billable_duration
FROM yourtable

输出（用于示例数据）

total_duration  billable_duration   non_billable_duration
850             650                 200

Demo on SQLFiddle