How to select every level with different user and user progress - mysql

Question

I wanted to make a learning apps with a completed questions progress track on each level. I have 2 tables which contain all the level with its question count, and a table that save an user progress (completed questions) on each level. Here is the record,
Level table:
+----------+----------------------+-------------+--------+
| id_level | name | jumlah_soal | id_sub |
+----------+----------------------+-------------+--------+
| 1 | Basic Level 1 | 5 | 1 |
| 2 | Basic Level 2 | 6 | 1 |
| 3 | Basic Level 3 | 7 | 1 |
| 8 | Intermediate Level 1 | 5 | 2 |
| 9 | Intermediate Level 2 | 5 | 2 |
| 10 | Intermediate Level 3 | 5 | 2 |
..........................................................
Progress Table:
+-----------------+---------+-------------+----------+
| id_progreslevel | id_user | completed | id_level |
+-----------------+---------+-------------+----------+
| 1 | 1 | 2 | 1 |
| 2 | 1 | 3 | 2 |
| 3 | 2 | 2 | 1 |
+-----------------+---------+-------------+----------+
and when I joined the tables with the following query
SELECT IFNULL(progreslevel.id_user, 1) as id_user,
-> level.*, IFNULL(progreslevel.completed, 0) as completedquestions
-> FROM level LEFT JOIN progreslevel
-> ON level.id_level = progreslevel.id_level
-> WHERE level.id_sub = 1
-> HAVING id_user = 1;
It queries what I wanted:
+---------+----------+---------------+-------------+--------+--------------------+
| id_user | id_level | name | jumlah_soal | id_sub | completed questions |
+---------+----------+---------------+-------------+--------+--------------------+
| 1 | 1 | Basic Level 1 | 5 | 1 | 2 |
| 1 | 2 | Basic Level 2 | 6 | 1 | 3 |
| 1 | 3 | Basic Level 3 | 7 | 1 | 0 |
+---------+----------+---------------+-------------+--------+--------------------+
BUT, when I tried to change to query a progress for user ID = 2, it became like this:
+---------+----------+---------------+-------------+--------+--------------------+
| id_user | id_level | name | jumlah_soal | id_sub | completed questions |
+---------+----------+---------------+-------------+--------+--------------------+
| 2 | 1 | Basic Level 1 | 5 | 1 | 2 |
| 2 | 3 | Basic Level 3 | 7 | 1 | 0 |
+---------+----------+---------------+-------------+--------+--------------------+
Yes, the Basic Level 2 is gone because user 2 hadn't done it yet but user 1 had.
This is where I'm stuck, I want to whichever user I choose, its always query all the level, even when the other user had done it. It should be like this:
+---------+----------+---------------+-------------+--------+--------------------+
| id_user | id_level | name | jumlah_soal | id_sub | completed questions |
+---------+----------+---------------+-------------+--------+--------------------+
| 2 | 1 | Basic Level 1 | 5 | 1 | 2 |
| 2 | 2 | Basic Level 2 | 6 | 1 | 0 |
| 2 | 3 | Basic Level 3 | 7 | 1 | 0 |
+---------+----------+---------------+-------------+--------+--------------------+
How do I achieve this?
Thanks in advance and Sorry if you got dizzy either at my explanation or database, I tried my best to translate it, so it's understandable

Answer 1

I'm not really sure that I understand the requirement, but I think you're after something like this...
SELECT l.*
, 2 id_user
, COALESCE(MAX(p.completed),0) completed_questions
FROM level l
LEFT
JOIN progress p
ON p.id_level = l.id_level
AND p.id_user = 2
WHERE l.id_sub = 1
GROUP
BY l.id_level;