Sqlserver 查询小技巧

--给列改名
方法1.
select sName as '姓名',sAge as '年龄' from student
方法2.
select sName '姓名',sAge '年龄' from student
方法3.
select '姓名'=sName,'年龄'=sAge from student

--Top Distinct
select top 2 sName,sAge,sSex from student
order by sAge

--百分之10个学生   如果有小数位数，直接进1
select top 10 percent sName,sAge,sSex
from student

select distinct * from student

select distinct sName from student
select distinct sName,sSex,sAge from student   --distinct只有当所有的列都重复时，才会剔除