Question

In MySql database I have table user

user_id | user_name
--------+----------
1       | Joe
2       | Anna
3       | Max

Table group

group_id | group_name
---------+----------
1        | Red
2        | Blue
3        | Green

Table group_member

group_member_id | user_id | group_id
----------------+---------+---------
1               | 1       | 2
2               | 3       | 2
3               | 1       | 3 
3               | 2       | 1

So… Member of the Red group is Anna, member of the Green gorup is Joe and members of the Blue group are Joe and max.

How can I get the list of users and their groups

User  | Group
------+------------
Joe   | Green, Blue
Anna  | Red
Max   | Blue 

Answer 1

SELECT u.user_name, GROUP_CONCAT(g.group_name)
FROM `user` u
inner JOIN group_member gm on gm.user_id = u.user_id
inner JOIN `group` g on g.group_id = gm.group_id
group by u.user_id