我们如何每次从 MySQL 表中随机获取不同的行或值集?

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2023-08-28 23:29:09 567浏览

我们如何每次从 MySQL 表中随机获取不同的行或值集?

mysql> Select * from Employee; +----+--------+--------+ | ID | Name | Salary | +----+--------+--------+ | 1 | Gaurav | 50000 | | 2 | Rahul | 20000 | | 3 | Advik | 25000 | | 4 | Aarav | 65000 | | 5 | Ram | 20000 | | 6 | Mohan | 30000 | | 7 | Aryan | NULL | | 8 | Vinay | NULL | +----+--------+--------+ 8 rows in set (0.00 sec)

现在,下面的查询将使用 RAND() 函数,并在查询中同时使用 ORDER BY 和 LIMIT 子句,返回随机不同的值或行集 -

mysql> Select * from employee ORDER BY RAND() LIMIT 4;
+----+-------+--------+
| ID | Name  | Salary |
+----+-------+--------+
| 5  | Ram   | 20000  |
| 4  | Aarav | 65000  |
| 6  | Mohan | 30000  |
| 8  | Vinay | NULL   |
+----+-------+--------+
4 rows in set (0.00 sec)

mysql> Select * from employee ORDER BY RAND() LIMIT 4;
+----+--------+--------+
| ID | Name   | Salary |
+----+--------+--------+
| 6  | Mohan  | 30000  |
| 8  | Vinay  | NULL   |
| 2  | Rahul  | 20000  |
| 1  | Gaurav | 50000  |
+----+--------+--------+
4 rows in set (0.03 sec)

mysql> Select * from employee ORDER BY RAND() LIMIT 4;
+----+-------+--------+
| ID | Name  | Salary |
+----+-------+--------+
| 3  | Advik | 25000  |
| 8  | Vinay | NULL   |
| 7  | Aryan | NULL   |
| 5  | Ram   | 20000  |
+----+-------+--------+
4 rows in set (0.00 sec)

从上面的结果集中可以看出,每次运行查询时,它都会返回一组随机不同的值或行。

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