Left Join Subquery Exclude GROUP BY with null result - mysql

Question

I am trying to create a query with a GROUP_CONCAT added as a new column in my current query, first here are my tables:
Users table
+----+----------+--------------+
| id | username | date_created |
+----+----------+--------------+
| 1 | user1 | 2000-03-16 |
| 2 | user2 | 2001-05-14 |
| 3 | user3 | 2002-01-13 |
| 4 | user4 | 2003-03-14 |
+----+----------+--------------+
Shifts table
+----+------------+--------------+
| id | shift_name | date_created |
+----+------------+--------------+
| 1 | shift1 | 2002-05-10 |
| 2 | shift2 | 2002-07-11 |
| 3 | shift3 | 2002-09-23 |
+----+------------+--------------+
Accounts table
+----+--------------+--------------+
| id | account_name | date_created |
+----+--------------+--------------+
| 1 | account1 | 2001-05-01 |
| 2 | account2 | 2001-05-02 |
| 3 | account3 | 2001-05-03 |
+----+--------------+--------------+
Shift Mapping table
+----+---------+----------+------------+
| id | user_id | shift_id | account_id |
+----+---------+----------+------------+
| 1 | 1 | 1 | 1 |
| 2 | 1 | 2 | 2 |
| 3 | 3 | 1 | 1 |
+----+---------+----------+------------+
basically, I want a query that gets all the user (to display in a table) with a custom column that shows all shift that is attach to that user(if there is no shift attach to that obviously has a null result)
Here is the query I've done so far:
SELECT users.id AS user_id, users.username, users.date_created,
GROUP_CONCAT(DISTINCT (t.shift_name)) AS shifts
FROM (`users`)
LEFT JOIN
(SELECT s.shift_name, sm.user_id FROM shift_map sm
LEFT JOIN shifts s ON sm.shift_id = s.id) t
ON users.id = t.user_id
GROUP BY user_id
ORDER BY `users`.`date_created` DESC;
Now there is no problem getting the users with a shift attach to it, my problem is that the users with no shifts attach to only returns 1 result which is caused by the GROUP BY user_id how can I exclude the users with no shift in the GROUP BY or how can I return all the users with attached shifts and with no attach shifts? Thanks.
Update
Here is the example result I want to see:
+---------+----------+--------------+----------------+
| user_id | username | date_created | shifts |
+---------+----------+--------------+----------------+
| 1 | user1 | 2000-03-16 | shift1,shift2 |
| 2 | user2 | 2001-05-14 | (NULL) |
| 3 | user3 | 2002-01-13 | shift1 |
| 4 | user4 | 2003-03-14 | (NULL) |
+---------+----------+--------------+----------------+
My problem in my query is that it only shows only 1 user with null shifts.

Answer 1

SELECT users.id AS user_id, users.username, users.date_created,
GROUP_CONCAT(DISTINCT (t.shift_name)) AS shifts
FROM (`users`)
LEFT JOIN
(SELECT s.shift_name, sm.user_id FROM mapping sm
LEFT JOIN shifts s ON sm.shift_id = s.id) t
ON users.id = t.user_id
GROUP BY username
ORDER BY user_id
+---------+----------+--------------+---------------+
| user_id | username | date_created | shifts |
+---------+----------+--------------+---------------+
| 1 | user1 | 2000-03-16 | shift1,shift2 |
| 2 | user2 | 2001-03-16 | NULL |
| 3 | user3 | 2002-03-16 | shift1 |
| 4 | user4 | 2003-03-16 | NULL |
+---------+----------+--------------+---------------+

Answer 2

My Bad, I can just use the simple LEFT JOIN:
SELECT users.id AS user_id, users.username, users.date_created,
GROUP_CONCAT(DISTINCT (shift.shift_name)) AS shifts
FROM (`users`)
LEFT JOIN shifts_map ON users.id = shifts_map.user_id
LEFT JOIN shifts ON shifts_map.shift_id = shift.id
GROUP BY user_id
ORDER BY `users`.`date_created` DESC;
I am just complicating the query, Forgot that the simple LEFT JOIN can do the trick. Thanks.