从datetime获取时间？ [英] Getting the hour from a datetime?

问题描述

如何从 datetime 中选择小时？

我正在寻找相当于Oracle的 TO_CHAR（d，'HH24'），将返回 17 2010-06- 23 17:22:31 。

I'm looking for the equivalent of Oracle's TO_CHAR( d, 'HH24' ), which would return 17 for 2010-06-23 17:22:31.

我试图找出最好的时间最好的答案/任务）在StackOverflow上使用 SQL 相关问题新的rel =nofollow noreferrer>数据浏览器。我得到它的工作，但我确定有一个更优雅的版本。

I tried to find out about the best time (best answer/questin-ration) to ask an SQL-related question on StackOverflow, using Data Explorer. I got it to work, but I'm sure there is a more elegant version.

Select
  Left( Convert(VARCHAR(10), creationDate, 8 ), 2 ) As hour,
  Convert(Float, Count(*)) / Count(Distinct p.parentId) As ratio
From posts p
Join postTags pt On ( pt.postId = p.parentId )
Join tags t On ( t.id = pt.tagId )
Where p.postTypeId = 2 And t.tagName = '##TagName##'
Group By Left( Convert(VARCHAR(10), creationDate, 8 ), 2 )
Order BY hour

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BTW，最好的时间似乎在 15:00 和<$ c之间$ c> 16:00 - 猜我问太晚了：）

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BTW, the best time seems to be between 15:00 and 16:00 - guess I'm asking too late :)

alt text http://img97.imageshack.us/img97/5421/besttimetoasksqlquestio.png

推荐答案

使用 DATEPART

select DATEPART(hour, DateTimeField) as Hour from Table

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