3.分页limit
select * from 表名 limit start,count
查询前3行男生信息
select * from students where gender=1 limit 0,3;
4.分组group by
select gender from students group by gender;
+--------+
| gender |
+--------+
| 男 |
| 女 |
| 中性 |
| 保密 |
+--------+
5.连接查询join……on
select * from 表1 inner或left或right join 表2 on 表1.列 = 表2.列
6.排序
select * from 表名 order by 列1 asc|desc [,列2 asc|desc,...]
7.优先级
and比or先运算，如果同时出现并希望先算or，需要结合()使用
8.自关联
创建areas表的语句如下：
create table areas(
aid int primary key,
atitle varchar(20),
pid int
);
从sql文件中导入数据
source areas.sql;
查询一共有多少个省
select count(*) from areas where pid is null;
总结：完整的select语句
select distinct *
from 表名
where ....
group by ... having ...
order by ...
limit start,count
执行顺序为：
from 表名
where ....
group by ...
select distinct *
having ...
order by ...
limit start,count
