mysql-SQL基础

sql在线练习网站 http://sqlzoo.net/wiki/SELECT_basics/zh

在线sql教程 https://www.1keydata.com/cn/sql/

1.模糊搜索

select * from world where continent like 'As%';

2.两个条件 and,or

select * from world where area=468 or area=28748;

3.限制 in

select * from world where area in (468,28748);

4.在范围内

select * from world where area between 0 and 200;

5.排序

select * from world where area between 0 and 200 order by area asc;

6.函数

select avg(area) from world where area between 0 and 200;

avg()平均值，count()计数，max()最大值，min()最小值，sum()总和

7.搜索不重复项

select distinct area from world where area between 0 and 200;

8.分组统计

select name,sum(area) from world group by name;

9.为函数设置条件

select name,sum(area) from world group by name having sum(area)<10000;

10.别名

select name my_name,sum(area) from world group by name having sum(area)<10000;