分页查询_limit

1 定义：分页显示查询信息。比如在百度中搜素一个关键词，会有很多记录，百度的页面设置一个页面只能显示10条记录，其余的记录会出现在第2页，第3页，第4页

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2 分页查询的语句：Limit 查询开始的索引，每页查询的条数。索引从0开始。
Limit是MySQL特有的，Oracle，SQLServer是其他的表示分页查询。
3 获得索引的公式
开始的索引=（页数-1）每页查询的条数
显示的start = 开始的索引+1
显示的end = 页数每页显示的条数
select * from employee limit 0,4; 第1页，检索表中1-4行
select * from employee limit 4,4; 第2页，检索表中5-8行
select * from employee limit 8,4; 第3页，检索表中9-12行
select * from employee limit 12,4; 第4页，检索表中13-16行

mysql> select * from employee;
+----+------+------+--------+--------+--------+
| id | name | age  | salary | phone  | in_dpt |
+----+------+------+--------+--------+--------+
|  1 | Tom  |   26 |   2500 | 119119 | dpt4   |
|  2 | Jack |   24 |   2500 | 120120 | dpt2   |
|  3 | Rose |   22 |   2800 | 114114 | dpt3   |
|  4 | Jim  |   35 |   3000 | 100861 | dpt1   |
|  5 | Mary |   21 |   3000 | 100101 | dpt2   |
|  6 | Alex |   26 |   3000 | 123456 | dpt1   |
|  7 | Ken  |   27 |   3500 | 654321 | dpt1   |
|  8 | Rick |   24 |   3500 | 987654 | dpt3   |
|  9 | Joe  |   31 |   3600 | 110129 | dpt2   |
| 10 | Mike |   23 |   3400 | 110110 | dpt4   |
| 11 | Jobs | NULL |   3600 |  19283 | dpt2   |
| 12 | Tony | NULL |   3400 | 102938 | dpt3   |
+----+------+------+--------+--------+--------+
12 rows in set (0.00 sec)

mysql> select * from employee limit 0,4;
+----+------+------+--------+--------+--------+
| id | name | age  | salary | phone  | in_dpt |
+----+------+------+--------+--------+--------+
|  1 | Tom  |   26 |   2500 | 119119 | dpt4   |
|  2 | Jack |   24 |   2500 | 120120 | dpt2   |
|  3 | Rose |   22 |   2800 | 114114 | dpt3   |
|  4 | Jim  |   35 |   3000 | 100861 | dpt1   |
+----+------+------+--------+--------+--------+
4 rows in set (0.00 sec)

mysql> select * from employee limit 4,4;
+----+------+------+--------+--------+--------+
| id | name | age  | salary | phone  | in_dpt |
+----+------+------+--------+--------+--------+
|  5 | Mary |   21 |   3000 | 100101 | dpt2   |
|  6 | Alex |   26 |   3000 | 123456 | dpt1   |
|  7 | Ken  |   27 |   3500 | 654321 | dpt1   |
|  8 | Rick |   24 |   3500 | 987654 | dpt3   |
+----+------+------+--------+--------+--------+
4 rows in set (0.00 sec)

mysql> select * from employee limit 8,4;
+----+------+------+--------+--------+--------+
| id | name | age  | salary | phone  | in_dpt |
+----+------+------+--------+--------+--------+
|  9 | Joe  |   31 |   3600 | 110129 | dpt2   |
| 10 | Mike |   23 |   3400 | 110110 | dpt4   |
| 11 | Jobs | NULL |   3600 |  19283 | dpt2   |
| 12 | Tony | NULL |   3400 | 102938 | dpt3   |
+----+------+------+--------+--------+--------+
mysql> select * from employee limit 12,4;
Empty set (0.00 sec)

4 如果只给定一个参数，它表示返回最大的记录行数目。换句话说，LIMIT n 等价于 LIMIT 0,n：
mysql> SELECT * FROM table LIMIT 5; //检索前 5 个记录行

ysql> select * from employee limit 5;
+----+------+------+--------+--------+--------+
| id | name | age  | salary | phone  | in_dpt |
+----+------+------+--------+--------+--------+
|  1 | Tom  |   26 |   2500 | 119119 | dpt4   |
|  2 | Jack |   24 |   2500 | 120120 | dpt2   |
|  3 | Rose |   22 |   2800 | 114114 | dpt3   |
|  4 | Jim  |   35 |   3000 | 100861 | dpt1   |
|  5 | Mary |   21 |   3000 | 100101 | dpt2   |
+----+------+------+--------+--------+--------+
5 rows in set (0.00 sec)

mysql> 

5 不支持limit最后一个数字为-1表示到末尾

mysql> select * from employee limit 5,-1;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '-1' at line 1
mysql>