这篇文章主要介绍了mysql中的rand()函数使用详解,是mysql入门学习中的基础知识,需要的朋友可以参考下 mysql rand()函数调用可以在0和1之间产生一个随机数： ? 1 2 3 4 5 6 7 mysql select rand( ), rand( ), rand( ); +------------------+-----------------
这篇文章主要介绍了mysql中的rand()函数使用详解,是mysql入门学习中的基础知识,需要的朋友可以参考下
mysql rand()函数调用可以在0和1之间产生一个随机数：
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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：
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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：
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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：
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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)
，