- 使用 order by rand() 隨機排序
root@127.0.0.1 : testdb【11:17:07】7 SQL->select * from city order by rand();
+---------+-----------+------------+---------------------+
| city_id | city_name | country_id | last_update |
+---------+-----------+------------+---------------------+
| 1010 | 大阪 | 1003 | 2019-07-13 04:14:15 |
| 1003 | 華盛頓 | 1001 | 2019-07-13 04:12:14 |
| 1001 | 旧金山 | 1001 | 2019-07-13 04:05:14 |
| 1004 | 波士頓 | 1001 | 2019-07-13 04:12:30 |
| 1013 | 倫敦 | 1005 | 2019-07-13 04:16:00 |
| 1009 | 東京 | 1003 | 2019-07-13 04:14:00 |
| 1007 | 廣州 | 1002 | 2019-07-13 04:13:21 |
| 1011 | 柏林 | 1004 | 2019-07-13 04:14:29 |
| 1006 | 南京 | 1002 | 2019-07-13 04:13:12 |
| 1008 | 珠海 | 1002 | 2019-07-13 04:13:28 |
| 1012 | 汉堡 | 1004 | 2019-07-13 04:15:45 |
| 1015 | 劍橋 | 1005 | 2019-07-13 04:17:36 |
| 1002 | 紐約 | 1001 | 2019-07-13 04:11:58 |
| 1005 | 北京 | 1002 | 2019-07-13 04:12:58 |
| 1014 | 牛津 | 1005 | 2019-07-13 04:17:19 |
+---------+-----------+------------+---------------------+
- 使用 order by rand() limit 3 隨機抽取3個樣本
root@127.0.0.1 : testdb【11:17:12】8 SQL->select * from city order by rand() limit 3;
+---------+-----------+------------+---------------------+
| city_id | city_name | country_id | last_update |
+---------+-----------+------------+---------------------+
| 1002 | 紐約 | 1001 | 2019-07-13 04:11:58 |
| 1008 | 珠海 | 1002 | 2019-07-13 04:13:28 |
| 1005 | 北京 | 1002 | 2019-07-13 04:12:58 |
+---------+-----------+------------+---------------------+
root@127.0.0.1 : testdb【11:17:26】9 SQL->select * from city order by rand() limit 3;
+---------+-----------+------------+---------------------+
| city_id | city_name | country_id | last_update |
+---------+-----------+------------+---------------------+
| 1005 | 北京 | 1002 | 2019-07-13 04:12:58 |
| 1014 | 牛津 | 1005 | 2019-07-13 04:17:19 |
| 1012 | 汉堡 | 1004 | 2019-07-13 04:15:45 |
+---------+-----------+------------+---------------------+
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