Question

我有两个基本查询，我需要总结：

Select hours, sum(hours) FROM table WHERE name='xxx' and Description='Worked'
Select hours2, sum(hours2) FROM table WHERE name='xxx' and Description2='Worked'

我已经尝试了UNION，它会得到每个查询的总数，但它不会合并它们。

表格设置为：

ID
姓名
小时
description
hours2
description2

我需要将小时与描述相关联，将小时2与描述2相关联，这就是为什么我有两个不同的查询。我需要总计小时和小时2的总和。

Answer 1

首先，你错过了group by，所以即使mysql没有抱怨它，你的hours和hours2值也毫无意义。其次，您UNION的结果可以放在派生子查询中，因此您将获得所需的总数：

SELECT SUM(hr) FROM
(
  Select sum(hours) as hr FROM table WHERE name='xxx' and Description='Worked'
  UNION ALL
  Select sum(hours2) as hr FROM table WHERE name='xxx' and Description2='Worked'
)a

Answer 2

您需要将联合放入子查询中：

SELECT  Hours,
        SUM(Hours) AS Hours,
        SUM(Hours2) AS Hours2
FROM    (   SELECT  Hours,
                    SUM(Hours) AS Hours,
                    0 AS Hours2
            FROM    Table
            WHERE   Name = 'xxx'
            AND     Description = 'Worked'
            GROUP BY Hours
            UNION ALL
            SELECT  Hours2,
                    0 AS Hours,
                    SUM(Hours2) AS Hours
            FROM    Table
            WHERE   Name = 'xxx'
            AND     Description2 = 'Worked'
            GROUP BY Hours2
        ) t
GROUP BY Hours;

两个查询的总和

2 个答案: