如何使用sql从日期字段按月分组 [英] How to group by month from Date field using sql

问题描述

如何从日期字段中仅按月分组(而不是按天分组)?

How can I group only by month from a date field (and not group by day)?

这是我的日期字段的样子:

Here is what my date field looks like:

2012-05-01

这是我当前的 SQL:

Here is my current SQL:

select  Closing_Date, Category,  COUNT(Status)TotalCount from  MyTable
where Closing_Date >= '2012-02-01' and Closing_Date <= '2012-12-31'
and Defect_Status1 is not null
group by  Closing_Date, Category

推荐答案

我会用这个:

SELECT  Closing_Date = DATEADD(MONTH, DATEDIFF(MONTH, 0, Closing_Date), 0), 
        Category,  
        COUNT(Status) TotalCount 
FROM    MyTable
WHERE   Closing_Date >= '2012-02-01' 
AND     Closing_Date <= '2012-12-31'
AND     Defect_Status1 IS NOT NULL
GROUP BY DATEADD(MONTH, DATEDIFF(MONTH, 0, Closing_Date), 0), Category;

这将按每个月的第一天分组，所以

This will group by the first of every month, so

`DATEADD(MONTH, DATEDIFF(MONTH, 0, '20130128'), 0)` 

将给出 '20130101'.我通常更喜欢这种方法，因为它将日期作为日期.

will give '20130101'. I generally prefer this method as it keeps dates as dates.

或者你可以使用这样的东西:

Alternatively you could use something like this:

SELECT  Closing_Year = DATEPART(YEAR, Closing_Date),
        Closing_Month = DATEPART(MONTH, Closing_Date),
        Category,  
        COUNT(Status) TotalCount 
FROM    MyTable
WHERE   Closing_Date >= '2012-02-01' 
AND     Closing_Date <= '2012-12-31'
AND     Defect_Status1 IS NOT NULL
GROUP BY DATEPART(YEAR, Closing_Date), DATEPART(MONTH, Closing_Date), Category;

这真的取决于你想要的输出是什么.(在您的示例中不需要关闭年份，但如果日期范围跨越年份边界，则可能需要).

It really depends what your desired output is. (Closing Year is not necessary in your example, but if the date range crosses a year boundary it may be).

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