【41-41】limit的使用

概述

1. 此为重点
2. limit是mysql特有的，其他数据库没有，不通用
3. Oracle有一个相同的机制，叫rownum
4. limit取结果集中的部分数据
5. 语法机制：limit statrIndex, length （起始位置，数量）
6. 可以完成分页查询

语句格式

select ...      5
from ...        1
where ...       2
group by ...    3
having ...      4
order by ...    6
limit ...       7

取出工资前五名的员工

mysql> select ename, sal from emp order by sal desc limit 0, 5;
+-------+---------+
| ename | sal     |
+-------+---------+
| KING  | 5000.00 |
| SCOTT | 3000.00 |
| FORD  | 3000.00 |
| JONES | 2975.00 |
| BLAKE | 2850.00 |
+-------+---------+
5 rows in set (0.00 sec)

取出工资在第四到第九的员工

mysql> select ename, sal from emp order by sal desc limit 3, 6;
+--------+---------+
| ename  | sal     |
+--------+---------+
| JONES  | 2975.00 |
| BLAKE  | 2850.00 |
| CLARK  | 2450.00 |
| ALLEN  | 1600.00 |
| TURNER | 1500.00 |
| MILLER | 1300.00 |
+--------+---------+
6 rows in set (0.00 sec)