MySql各种查询

1.简单查询

　　select * from info;

　　select Code as ‘代号‘,name as ‘姓名‘ from info;

2.条件查询

　　select * from car where code = ‘c002‘;

　　select * from car where brand =‘b001‘ and power = 130; #或用or

3.模糊查询

　　select * from car where name like ‘%奥迪%‘;  %代表任意多个字符包括0个 _代表一个字符

4.排序查询

　　select * from car order by brand, powers desc; asc升序默认可以不写

5。范围查询

　　select * from car where price between 40 and 60;

6.离散查询

　　select * from car where code in(‘coo1‘,‘c003‘,‘c005‘,‘c007‘);

　　select * from car where code not in(‘coo1‘,‘c003‘,‘c005‘,‘c007‘);

7.统计查询（聚合函数）

　　select count(code) from car;　　查询数据条数也可以count(*)这么写，性能低

　　select sum(price) from car;　　求和

　　select max(code) from car;　　最大　　

　　select min(brand) from car;　　最小

　　select avg(price) from car;　　平均

8.分页查询

　　select * from Car limit (n-1)*5,5  #第n页，每页显示五条数据

9.去重查询

　　select distinct Brand from Car

10.分组查询　

　　select brand,count(*),Brand from Car group by Brand 　　#把brand列的相同值组合起来，并这一条数据对该列或或其他列进行操作例如求平均值
　　select Brand from Car group by Brand having count(*)>3 #分组之后根据条件查询使用having 不使用where

MySql各种查询

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