其中表达式group by(col)与group by(col)具有表达式

时间:2018-07-07 09:03:32

标签: group-by sql-server-2014 having ssms-2012

样本表:

 create table #dev (name varchar(20), team varchar(10), qualification varchar(10))

 insert into #dev values
  ('a','t','be')
 ,('b','d','bsc')
 ,('c','p','be')
 ,('d','j','be')
 ,('e','d','bsc')
 ,('f','j','bsc')
 ,('g','d','be')
 ,('h','j','be')
 ,('i','d','bsc')
 ,('j','j','bsc')
 ,('k','d','be')

 select team,qualification,COUNT(qualification ) from #dev
 group by team,qualification having qualification = 'be'

 select team,qualification,COUNT(qualification ) from #dev
 where qualification = 'be'
 group by team,qualification

它们返回相同的结果。在这里,我有一个疑问。即:

哪个查询有效..? 专家首选哪种查询?

答案对我们将来会非常有用。

谢谢, 泰米尔语(TamilPugal)。

0 个答案:

没有答案
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