SQL 关键字:
1,CAST:
SELECT CAST(productID as varchar(30)+':'+productName) as Name
from Prouduct --把 int 转为 varchar 类型去处理. (相当于string.Formate()方法. )
2, CASE:
SELECT studentName,
case Score
when Score<60 then '不及格'
when Score>90 then '良'
else '优'
end
from StudentScore --CASE: 对某个字段分出等级.
3, INTO:
into的作用: (1),创建新表,(2),把select 得到的数据插入新表中. (note:必须要有 create table的权限.)
eg:
select *
into newtable
from UserInfo
4,UNION:
用UNION 查询,则会去除重复的行, 而如果用All ,则不会.
