Question

拥有包含此值的表格：

name     | executing | failed |
-------------------------------
task1         0          1
task2         1          0
task3         1          0
task4         0          0

使用我想要的查询：

executing任务的总量（示例中为2，task2和task3）
failed任务的总量（示例中为1，task1）
待处理任务的总数（executing=0和failed=0，示例中的1，task4）

我可以通过以下查询获得前两个：

SELECT IFNULL(SUM(executing), 0) Executing, IFNULL(SUM(failed), 0) Failed FROM mytable;

如何扩展我的查询以便我可以使用待处理任务的总和获得另一列？

提前致谢

预期产出：

executing | failed | pending
----------------------------
     2         1          1

Answer 1

您没有指定结果的方式。我会这样做：

select (case when executing = 1 and failed = 0 then 'Executing'
             when failed = 1 then 'Failed'
             when executing = 0 and failed = 0 then 'Pending'
             else 'Unknown'
        end) as status, count(*) as cnt
from t
group by status;

您还可以使用条件聚合轻松转动数据：

select sum(executing = 1 and failed = 0) as Executing,
       sum(failed = 1) as Failed,
       sum(executing = 0 and failed = 0) as Pending
from t;

这使用MySQL速记将布尔表达式视为数字 - “1”表示true，“0”表示false。

Answer 2

SELECT SUM(executing) AS Executing
    , SUM(failed) as Failed
    , SUM(CASE 
        WHEN executing = 0 AND failed = 0 THEN 1
        ELSE 0 END
    ) AS Pending
FROM mytable;

查询以使用条件对列的某些值求和

2 个答案: