Question

I have the following query (user_id isn’t and can’t be primary key as there are many entries from each user depending on another column of the table). I used duplicate key but doesnt work. It still adds a new row. Any thoughts?

INSERT INTO profile (user_id, correct) VALUES(". $user_id . ", correct + 1)
ON DUPLICATE KEY UPDATE correct=correct+1

EDIT
So if row exists for this user_id, I want to go update this entry and SET correct = correct+1 and not make a new entry with user_id and correct=1 again

Answer 1

Try this:

INSERT IGNORE INTO profile (user_id, correct)
VALUES ($user_id, 0);

UPDATE profile SET correct = correct + 1 
WHERE  user_id = $user_id;  -- updates 0 to 1

Or:

UPDATE profile SET correct = correct + 1 
WHERE  user_id = $user_id;

If not found:

INSERT INTO profile (user_id, correct)
VALUES ($user_id, 1);

I prefer the second variant.
The first variant requires that the user_id has a UNIQUE constraint. (PRIMARY KEY counts.)