sql limit 的使用

1. limit 用来获取一张表中的某些数据
2. limit 只有 在Mysql 数据库中存在 不通用
3. limit 出现在sql语句的最后一个

3.案例：找出前五条记录
// 两条查询语句结果一样，开始标0 可以省略
mysql> select ename from emp limit 0,5;
mysql> select ename from emp limit 5;
+--------+
| ename  |
+--------+
| SIMITH |
| ALLEN  |
| WARD   |
| JONES  |
| MARTIN |
+--------+
5 rows in set (0.00 sec)

4.案例：按照工资降序排列，只取前五个
mysql> select ename, sal from emp order by sal desc limit 5;
+-------+------+
| ename | sal  |
+-------+------+
| KING  | 5000 |
| FORD  | 3000 |
| SCOTT | 3000 |
| JONES | 2975 |
| BLAKE | 2850 |
+-------+------+
5. 工资按照降序 查询出3到9的工资   索引是0开始的
mysql> select ename, sal from emp order by sal desc limit 2,7;
+--------+------+
| ename  | sal  |
+--------+------+
| SCOTT  | 3000 |
| JONES  | 2975 |
| BLAKE  | 2850 |
| CLARK  | 2450 |
| ALLEN  | 1600 |
| TURNER | 1500 |
| MILLER | 1300 |
+--------+------+
7 rows in set (0.00 sec)