如何使用SQL从日期字段按月分组

如何仅从日期字段中按月分组（而不是按天分组）？

我的日期字段如下所示：

2012-05-01

这是我当前的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

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;

这将在每个月的第一天分组

`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，您可以使用如下所示的内容：

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;

这实际上取决于您所需的输出是什么。（在您的示例中，不需要关闭年份，但是如果日期范围超出了年份范围，则可能会是）。

使用DATEPART函数从日期中提取月份。

因此，您将执行以下操作：

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

我使用FORMAT函数来完成此任务：

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

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

DATEPART函数在MySQL 5.6上不起作用，而是使用MONTH（'2018-01-01'）

试试这个：

select min(closing_date), date_part('month',closing_date) || '-' || date_part('year',closing_date) AS month,
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, Category,
ORDER BY 1

通过这种方式，您可以按合并的日期格式进行分组，并以-

SELECT  to_char(Closing_Date,'MM'), 
        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 Category;

上面的SQL Server 2012版本，

SELECT  format(Closing_Date,'yyyy-MM') as ClosingMonth,
        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 format(Closing_Date,'yyyy-MM'), Category;

您可以通过使用Year（），Month（）Day（）和datepart（）来实现。

在您的示例中，这将是：

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 Year(Closing_Date), Month(Closing_Date), Category

尝试以下代码

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;