mysql rand()函数调用可以在0和1之间产生一个随机数：

mysql>  ｓｅｌｅｃｔ RAND( ), RAND( ), RAND( );+------------------+-----------------+------------------+| RAND( )          | RAND( )         | RAND( )          |+------------------+-----------------+------------------+| 0.45464584925645 | 0.1824410643265 | 0.54826780459682 |+------------------+-----------------+------------------+1 row in set (0.00 sec)

当调用一个整数参数时，RAND()使用该随机数发生器种子值。每次在给定值种子生成，RAND()会产生一个可重复的一系列数字：

mysql>  ｓｅｌｅｃｔ RAND(1), RAND( ), RAND( );+------------------+------------------+------------------+| RAND(1 )         | RAND( )          | RAND( )          |+------------------+------------------+------------------+| 0.18109050223705 | 0.75023211143001 | 0.20788908117254 |+------------------+------------------+------------------+1 row in set (0.00 sec)

可以使用ORDER BY RAND()，随机组行或值如下：

要了解ORDER BY RAND()函数, 假设empLOYEE_TBL的表有以下记录：

mysql> ｓｅｌｅｃｔ * FROM employee_tbl;+------+------+------------+--------------------+| id   | name | work_date  | daily_typing_pages |+------+------+------------+--------------------+|    1 | John | 2007-01-24 |                250 ||    2 | Ram  | 2007-05-27 |                220 ||    3 | Jack | 2007-05-06 |                170 ||    3 | Jack | 2007-04-06 |                100 ||    4 | Jill | 2007-04-06 |                220 ||    5 | Zara | 2007-06-06 |                300 ||    5 | Zara | 2007-02-06 |                350 |+------+------+------------+--------------------+7 rows in set (0.00 sec)

现在使用以下目录：

mysql> ｓｅｌｅｃｔ * FROM employee_tbl ORDER BY RAND();+------+------+------------+--------------------+| id   | name | work_date  | daily_typing_pages |+------+------+------------+--------------------+|    5 | Zara | 2007-06-06 |                300 ||    3 | Jack | 2007-04-06 |                100 ||    3 | Jack | 2007-05-06 |                170 ||    2 | Ram  | 2007-05-27 |                220 ||    4 | Jill | 2007-04-06 |                220 ||    5 | Zara | 2007-02-06 |                350 ||    1 | John | 2007-01-24 |                250 |+------+------+------------+--------------------+7 rows in set (0.01 sec)mysql> ｓｅｌｅｃｔ * FROM employee_tbl ORDER BY RAND();+------+------+------------+--------------------+| id   | name | work_date  | daily_typing_pages |+------+------+------------+--------------------+|    5 | Zara | 2007-02-06 |                350 ||    2 | Ram  | 2007-05-27 |                220 ||    3 | Jack | 2007-04-06 |                100 ||    1 | John | 2007-01-24 |                250 ||    4 | Jill | 2007-04-06 |                220 ||    3 | Jack | 2007-05-06 |                170 ||    5 | Zara | 2007-06-06 |                300 |+------+------+------------+--------------------+7 rows in set (0.00 sec)

标签： rand函数的使用方法及实例