T-SQL语句学习（一）

SQL中case语句的使用：

 

use TeachingManageSYS
 go
 select *, 
 case when Sage>=20 then '成人'
   when Sage<20 then '少年'
   else 'hard'
 end FrenightType
from StudentInfo
where Ssex='男'
order by FrenightType asc
go