获取DateTime的T-SQL代码仅包含来自任何DateTime的Month和Year [英] T-SQL code to get a DateTime contain only Month and Year from any DateTime

问题描述

给定一个表 Event 包含一个名为 EventTime 类型为DateTime的字段，该值将包含日期和时间元素，我需要创建一个汇总查询，计算每个月内的事件数。

Given a table Event containing a field called EventTime of type DateTime and that the value will contain both date and time elements, I need create a summary query which counts the number of events in each month.

分组依据字段的结果类型也必须是日期时间0时间元素，并设置为每月的第一天。

The resulting type of the Group By field must also be Date Time with a 0 time element and set to 1st day of the month.

这是我迄今为止，但它不是很优雅，我不知道它特别有效。 p>

This is what I have so far but its not very elegant and I'm not sure its particularly efficient.

  SELECT COUNT(1) AS [CountOfEvents],
         DATEADD(d, 1 - DAY(EventTime), DATEADD(dd, 0, DATEDIFF(dd, 0, EventTime))) AS [Month]
    FROM [Event]
GROUP BY DATEADD(d, 1 - DAY(EventTime), DATEADD(dd, 0, DATEDIFF(dd, 0, EventTime)))

更好的建议，以提高效率或优雅？

Better suggestions for either more efficiency or elegance?

推荐答案

这个楼层到这个月：

select dateadd(month,datediff(m,0,GETDATE()),0);

输出：

-----------------------
2009-10-01 00:00:00.000

(1 row(s) affected)

所以请尝试：

SELECT
   COUNT(*) as CountOF
    ,dateadd(month,datediff(m,0,EventTime),0)
    FROM [Event]
    GROUP BY dateadd(month,datediff(m,0,EventTime),0)
    ORDER BY 2

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