将子查询结果组合为文本

Question

问题：我想将子查询的结果组合为文本字段，结果用逗号（或任何符号确实）分隔成主查询的结果。

示例：

表1：

 +----------+---------+
 |  user_ID | user    |
 +----------+---------+
 |        1 |   Smith |
 +----------+---------+
 |        2 |   Jones |
 +----------+---------+

表1：

 +----------+---------+
 |  user_ID | roles   |
 +----------+---------+
 |        1 |   Admin |
 +----------+---------+
 |        2 |   Staff |
 +----------+---------+
 |        2 |   Admin |
 +----------+---------+
 |        2 |   Super |
 +----------+---------+
 |        1 |   Other |
 +----------+---------+

结果将是：

 +----------+---------+----------------------------+
 |  user_ID | user    |   roles                    |
 +----------+---------+----------------------------+
 |        1 |   Smith |    Admin, Other            |
 +----------+---------+----------------------------+
 |        2 |   Jones |    Staff, Admin, Super     |
 +----------+---------+----------------------------+

非常感谢任何帮助。

Answer 1

试试这个：

select t1.user_id, t1.user, group_concat(t2.roles separator ', ') roles
from t1
join t2 on t1.user_id = t2.user_id
group by t1.user_id, t1.user

查看GROUP_CONCAT文档以获取更多信息。

Answer 2

试试这个并告诉我它是否有帮助：

select a.user_id, a.user, group_concat(b.roles) as roles
from table1 as a
join table2 as b on a.user_id = b.user_id
group by a.user_id

Answer 3

select a.user_ID,a.user,b.roles 
from table1 as a, table2 as b 
where a.user_ID=b.user_ID