group_concat的用法

目标：一列(user_id)相同，另一类(user_name)不相同，希望根据user_id拼接user_name

步骤：

原始数据：

+---------+-----------------------------+
| user_id | user_name   | principal  |
+---------+-----------------------------+
|       1 | arina.kan         |  3M          |
|       2 | thong             |  L'Oreal    |
|       3 | suboko            |  xiaomi    |
|       3 | suboko            |  huawei  |
|       3 | suboko            |  3M          |
|       4 | alisya            |  CPD
|       5 | peggy.zhu         |  PDD
|       6 | woof              |  swisse
|       7 | liuwen            |  3M
|       8 | caocao            |  HP
|       9 | kate              |  beiersdorf
|      10 | tanglin           |  aveeno
+---------+-----------------------------+

使用group_concat

mysql> select user_id,GROUP_CONCAT(user_name) from sp_user_principal_tab GROUP BY user_id limit 10;
+---------+-----------------------------+
| user_id | GROUP_CONCAT(user_name)     |
+---------+-----------------------------+
|       1 | arina.kan                    |
|       2 | thong                 |
|       3 | suboko,suboko,suboko |
|       4 | alisya               |
|       5 | peggy.zhu                   |
|       6 | woof                       |
|       7 | liuwen                   |
|       8 | caocao                  |
|       9 | kate                 |
|      10 | tanglin                 |
+---------+-----------------------------+
10 rows in set (0.01 sec)