备注:测试数据库版本为MySQL 8.0

一.需求

给结果集分页或滚动显示整个结果集

例如，先返回表emp中的前5行工资，然后是下5行，依此类推。目标是允许用户一次能够查看5个记录，每次单击"下一页"按钮都会向前桂东5个记录。

二.解决方案

在SQL中，由于没有“第一个”、“最后一个”及“下一个”的概念，所以必须对要处理的行按某种方式排序，只有如此，才会准确地返回一定范围内记录。

-- MySQL  limit offset解决方案
-- offset表示跳过几行
select sal
from emp 
order by sal
limit 5 offset 0
;


select sal
from emp 
order by sal
limit 5 offset 5
;

-- MySQL 8.0 分析函数解决方案
select sal
   from (
select row_number() over (order by sal) as rn,
       sal
   from emp
        ) x
where rn between 1 and 5;


select sal
   from (
select row_number() over (order by sal) as rn,
       sal
   from emp
        ) x
where rn between 6 and 10;

测试记录

mysql> select sal
    -> from emp
    -> order by sal
    -> limit 5 offset 0
    -> ;
+---------+
| sal     |
+---------+
|  800.00 |
|  950.00 |
| 1100.00 |
| 1250.00 |
| 1250.00 |
+---------+
5 rows in set (0.00 sec)

mysql> select sal
    -> from emp
    -> order by sal
    -> limit 5 offset 5
    -> ;
+---------+
| sal     |
+---------+
| 1300.00 |
| 1500.00 |
| 1600.00 |
| 2450.00 |
| 2850.00 |
+---------+
5 rows in set (0.00 sec)

mysql>
mysql> select sal
    ->    from (
    -> select row_number() over (order by sal) as rn,
    ->        sal
    ->    from emp
    ->         ) x
    -> where rn between 1 and 5;
+---------+
| sal     |
+---------+
|  800.00 |
|  950.00 |
| 1100.00 |
| 1250.00 |
| 1250.00 |
+---------+
5 rows in set (0.00 sec)

mysql> select sal
    ->    from (
    -> select row_number() over (order by sal) as rn,
    ->        sal
    ->    from emp
    ->         ) x
    -> where rn between 6 and 10;
+---------+
| sal     |
+---------+
| 1300.00 |
| 1500.00 |
| 1600.00 |
| 2450.00 |
| 2850.00 |
+---------+
5 rows in set (0.00 sec)