mysql>>随机返回结果集 >>rand的使用

表结构
+--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date  |
+--------+------------+------------+-----------+--------+------------+
|  10001 | 1953-09-02 | Georgi     | Facello   | M      | 1986-06-26 |
|  10002 | 1964-06-02 | Bezalel    | Simmel    | F      | 1985-11-21 |
|  10003 | 1959-12-03 | Parto      | Bamford   | M      | 1986-08-28 |
|  10004 | 1954-05-01 | Chirstian  | Koblick   | M      | 1986-12-01 |
|  10005 | 1955-01-21 | Kyoichi    | Maliniak  | M      | 1989-09-12 |
|  10006 | 1953-04-20 | Anneke     | Preusig   | F      | 1989-06-02 |
|  10007 | 1957-05-23 | Tzvetan    | Zielinski | F      | 1989-02-10 |
|  10008 | 1958-02-19 | Saniya     | Kalloufi  | M      | 1994-09-15 |
|  10009 | 1952-04-19 | Sumant     | Peac      | F      | 1985-02-18 |
|  10010 | 1963-06-01 | Duangkaew  | Piveteau  | F      | 1989-08-24 |
+--------+------------+------------+-----------+--------+------------+

#随机返回2行结果集
select *
from employees
order by rand()
limit 2;

+第一次的执行结果集

--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date  |
+--------+------------+------------+-----------+--------+------------+
| 454095 | 1952-02-28 | Keiichiro  | Kalefeld  | M      | 1985-04-10 |
|  56999 | 1956-01-23 | Udi        | Wiegley   | M      | 1985-09-26 |
+--------+------------+------------+-----------+--------+------------+

+第二次执行结果集

--------+------------+------------+-----------+--------+------------+
| emp_no | birth_date | first_name | last_name | gender | hire_date  |
+--------+------------+------------+-----------+--------+------------+
| 231522 | 1955-02-08 | Saeed      | Kaminger  | M      | 1995-07-12 |
| 456029 | 1964-10-25 | Breannda   | Haldar    | M      | 1991-07-23 |
+--------+------------+------------+-----------+--------+------------+