SQL 一條SQL語句 統計 各班總人數、男女各總人數 、該班級男女 比例

 

 

select count(*) as numOfTotal,
sum(case when t.[gender]='male' then 1 else 0 end) as numOfMale , --男生人數
sum(case when t.[gender]='female' then 1 else 0 end) numOfFemale, --女生人數
sum(case when t.[gender]='male' then 1 else 0 end)*1.0/count(*) as percentOfMale,
sum(case when t.[gender]='female' then 1 else 0 end)*1.0/count(*) as perscentOfFemale
from
(SELECT a.[userid],a.[module],a.[amount],b.[name],b.[gender]
  FROM [PracticeSQL].[dbo].[module] a inner join [PracticeSQL].[dbo].[user] b
  on a.[userid]=b.[userid]) t 

 

輸出結果：

numOfTotal numOfMale numOfFemale percentOfMale perscentOfFemale
18 14 4 0.777777777777 0.222222222222

 

參考：http://blog.csdn.net/guoxingege/article/details/48054815