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;