如何使用sql从Date字段按月分组

Question

如何从日期字段中按月分组(而不是按日分组)？

这是我的日期字段的样子:

2012-05-01

这是我目前的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

Answer 1

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;

这将按每月的第一天分组,所以

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

会给'20130101'.我通常更喜欢这种方法,因为它将日期保留为日期.

或者你可以使用这样的东西:

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;

这取决于你想要的输出.(在您的示例中不需要结算年份,但如果日期范围跨越年份边界,则可能是).

Answer 2

使用DATEPART函数从日期中提取月份.

所以你会做这样的事情:

SELECT DATEPART(month, Closing_Date) AS Closing_Month, COUNT(Status) AS TotalCount
FROM t
GROUP BY DATEPART(month, Closing_Date)

Answer 3

我用FORMAT函数来完成这个:

select
 FORMAT(Closing_Date, 'yyyy_MM') AS Closing_Month
 , count(*) cc 
FROM
 MyTable
WHERE
 Defect_Status1 IS NOT NULL
 AND Closing_Date >= '2011-12-01'
 AND Closing_Date < '2016-07-01' 
GROUP BY FORMAT(Closing_Date, 'yyyy_MM')
ORDER BY Closing_Month

Answer 4

通过增加MONTH(date_column)在GROUP BY。

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 MONTH(Closing_Date), Category