问题描述
如果您使用该怎么办:
select SUM(WordCount) as 'words per day'
from @WordsCount
group by DateAdded
我不明白您为什么还要按字数分组…。
另外,由于DateAdded
可能是DATETIME
包含时间部分的列,因此您可能希望仅按日期分组:
select SUM(WordCount) as 'words per day'
from @WordsCount
group by CAST(DateAdded AS DATE)
如果我尝试此,查询工作正常....
DECLARE @WordsCnt TABLE (WordCount INT, DateAdded DATETIME)
INSERT INTO @wordsCnt(WordCount, DateAdded)
VALUES(96, '2008-11-07 09:16:31.810'),
(32, '2008-11-07 15:26:27.547'),
(25, '2008-11-23 16:05:39.640'),
(62, '2008-12-03 12:33:03.110')
select CAST(DateAdded AS DATE), SUM(WordCount) as 'words per day'
from @WordsCnt
group by CAST(DateAdded AS DATE)
并产生输出:
2008-11-07 128
2008-11-23 25
2008-12-03 62
解决方法
这应该很简单,但是让我受益匪浅。
我所拥有的只是一个只有两列的表格,如下所示:
WordCount DateAdded
`````````````````````````````
96 2008-11-07 09:16:31.810
32 2008-11-07 15:26:27.547
25 2008-11-23 16:05:39.640
62 2008-12-03 12:33:03.110
等等。
我想计算 每天 的 总字数 -我将它们按日期添加分组并选择WordCount的总和,最后得到语法错误(wordcount必须在group
by子句中),但是现在我得到的天数为null
这是我的查询:
select SUM(WordCount) as 'words per day' from @WordsCount group by DateAdded,WordCount
这只是选择null。我怎么知道怎么了?
谢谢。