Question

我想使用Microsoft SQL Server Management Studio从数据库中获取一些数据。我想做一些计算：

每天我有2个不同的数据点。我想要的是添加一个新的数据点，它是两个数据点的总和。

在我的示例中，我想编写以下任务：

每个＆＃39;日期＆＃39;我想要一个新的数据点（让我们称之为category3），这是总和af＆＃39;数据＆＃39;来自＆＃39; category1＆＃39;和＆＃39;类别2＆＃39;。我的代码：

 SELECT   
     [Date], [category], [Data]
 FROM 
     [ ... ]
 WHERE 
     category IN ('category1', 'category2')
 ORDER BY
     AsOfDate

Answer 1

使用UNION ALL：

SELECT  [Date],
        [category],
        [Data]
FROM [ ... ]
WHERE category  IN ('category1','category2')
UNION ALL
SELECT  [Date],
        'category3',
        SUM([Data])
FROM [ ... ]
WHERE category  IN ('category1','category2')
GROUP BY [Date];

Answer 2

您是否只想要一个group by的简单where查询？

 select [Date], SUM(Data)
 from [ ... ]
 Where category  in ('category1','category2')
 group by AsOfDate

Answer 3

 SELECT t1.[Date],
        t1.[Data], 
        t2.[Data],
        t1.[Data] + t2.[Data] as [category3]
 FROM [ ... ] t1 inner join [ ... ] t2 on t1.[Date] = t2.[Date] and t1.category = 'category1' and t2.category = 'category2'
 order by AsOfDate

SQL Server

3 个答案: