T-SQL简单查询语句（模糊查询）

  T-SQL简单查询语句

 简单查询：

 1.最简单查询（查所有数据）
 select * from 表名； 注：* 代表所有列
 select * from info

 2.查询指定列
 select code,name from info

 3.修改结果集的列名
 select code as '代号',name as '姓名' from info

 4.条件查询
 select * from info where code='p003'

 5.多条件查询
 查询info表中code为p003或者nation为n001的所有数据
 select * from info where code='p003' or nation='n001'
 查询info表中code为p004并且nation为n001的数据
 select * from info where code='p004' and nation='n001'

 6.范围查询
 select * from car where price>=40 and price<=60
 select * from car where price between 40 and 60

 7.离散查询
 查询汽车价格在（10,20,30,40,50,60）中出现的汽车信息
 select * from car where price=10 or price=20 or price=30 or price=40 or price=50 or price=60

 select * from car where price in(10,20,30,40,50,60)
 select * from car where price not in(10,20,30,40,50,60)

 8.模糊查询（关键字查询）
 查询car表里面名称包含奥迪的
 select * from car where name like '%奥迪%' %任意n个字符
 查询car中名称第二个字符为‘马’的汽车
 select * from car where name like '_马%' _任意一个字符

9.排序查询
select * from car order by price asc asc升序（省略）
select * from car order by oil desc desc降序

先按照brand升序排，再按照price降序排
select * from car order by brand,price desc

 10.去重查询
 select distinct brand from car

 11.分页查询
 一页显示10条 当前是第3页
 select * from chinastates limit 20,10

 一页显示m条 当前是第n页
 limit (n-1)*m，m

 12.聚合函数（统计函数）
 select count(areacode) from chinastates #查询数据总条数
 select sum(price) from car #求和
 select avg(price) from car #求平均
 select max(price) from car #求最大值
 select min(price) from car #求最小值 

13.分组查询
查询汽车表中每个系列下有多少个汽车
select brand,count(*) from car group by brand

查询汽车表中卖的汽车数量大于1的系列 select brand from car group by brand having count(*)>1