向 mySQL GROUP_CONCAT 语句添加内连接

Posted 2023-02-24

【中文标题】向 mySQL GROUP_CONCAT 语句添加内连接

【英文标题】：Add an inner join to mySQL GROUP_CONCAT statement

【发布时间】：2012-04-22 11:36:43

【问题描述】：

问题：我有一个按预期工作的 GROUP_CONCAT 查询，但我想让 concat 成为连接答案，而不是原始 ID 字段。

当前查询：

SELECT user.user_id, user.user, GROUP_CONCAT(user_roles.roleID separator ', ') roles
FROM user
JOIN user_roles ON user.user_ID = user_roles.user_ID
GROUP BY users.user_ID, users.user

给出结果：

+----------+---------+----------------------------+
|  user_ID | user    |   roles                    |
+----------+---------+----------------------------+
|        1 |   Smith |    1, 3                    |
+----------+---------+----------------------------+
|        2 |   Jones |    1, 2, 3                 |
+----------+---------+----------------------------+

期望的结果：

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

用户表：

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

*users_roles 表：*

+----------+---------+
|  user_ID | role_ID |
+----------+---------+
|        1 |   1     |
+----------+---------+
|        2 |   1     |
+----------+---------+
|        2 |   2     |
+----------+---------+
|        2 |   3     |
+----------+---------+
|        1 |   3     |
+----------+---------+

角色表：

+----------+-----------+
|  role_ID | role_name |
+----------+-----------+
|        1 |   Admin   |
+----------+-----------+
|        2 |   Staff   |
+----------+-----------+
|        3 |   Other   |
+----------+-----------+

【参考方案1】：

尝试以下查询

SELECT user.user_id, user.user, GROUP_CONCAT(roles.role_name  separator ', ') roles
FROM user
JOIN user_roles ON user.user_ID = user_roles.user_ID
JOIN roles ON user_roles.role_ID= user_roles.role_ID
GROUP BY users.user_ID, users.user