Question

I need to get quize title, quize description, quize questions and answers for each questions. My table structure is:

quizes
quize_id | title | user_id | ...

questions
questions_id | quize_id | question | ...

question_answers
answer_id | question_id | user_id | answer | ...

I can use join

SELECT * FROM quizes JOIN questions q ON q.quize_id=quizes.quize_id JOIN question_answers a ON a.question_id=q.question_id

But the problem with this is that I will get in results many rows with redundant data. For example each row will carry field title,user_id, … Another way is to make for each question extra query to get answers. Is there any better way? Should I use only 1 query or more?

Answer 1

I found also another way which return all data I need, including user details for each question:

SELECT 
    question, 
    group_concat(qa.answer SEPARATOR ',') as answers,
    group_concat(qa.user_id SEPARATOR ',') as userIds,
    group_concat(up.nickname SEPARATOR ',') as nickname
FROM quize_questions qq
INNER JOIN question_answers qa ON qa.question_id=qq.question_id
INNER JOIN user_profile up ON up.user_id = qa.user_Id
GROUP BY qq.question_id

I am just not sure if this is the right way. I am worried about speed.