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 程式師世界 >> 數據庫知識 >> MYSQL數據庫 >> MySQL綜合教程 >> MySQL中的RAND()函數應用詳解

MySQL中的RAND()函數應用詳解

編輯:MySQL綜合教程

MySQL中的RAND()函數應用詳解。本站提示廣大學習愛好者:(MySQL中的RAND()函數應用詳解)文章只能為提供參考,不一定能成為您想要的結果。以下是MySQL中的RAND()函數應用詳解正文


MySQL RAND()函數挪用可以在0和1之間發生一個隨機數:

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

當挪用一個整數參數時,RAND()應用該隨機數產生器種子值。每次在給定值種子生成,RAND()會發生一個可反復的一系列數字:

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

可使用ORDER BY RAND(),隨機組行或值以下:

要懂得ORDER BY RAND()函數, 假定EMPLOYEE_TBL的表有以下記載:

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)

如今應用以下目次:

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)


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