Sql query null value insertion - sql

Question

Sql Query
SELECT respondant.respondant_firstname as first_name,
question.question_id as question_id,
answer.answer_id,
answer.answer_text,
answer.answer_rate,
answer.answer_nps,
question_radio.question_radio_text as opt
FROM question
LEFT JOIN answer on answer.answer_question_id = question.question_id
LEFT JOIN question_radio on answer.answer_question_radio_id = question_radio.question_radio_id
LEFT JOIN respondant on answer.answer_respondant_id = respondant.respondant_id
WHERE question.question_feedback_id = 1
ORDER BY question.question_id, answer.answer_id
Output:
first_name question_id answer_id answer_text answer_rate answer_nps opt
RM 1 1 5 NULL NULL
Y 1 3 0 NULL NULL
Ben 1 5 0 NULL NULL
akash 1 8 2.5 NULL NULL
RM 2 2 0 4 NULL
Y 2 4 0 3 NULL
Ben 2 6 0 0 NULL
akash 2 9 0 0 NULL
Ben 3 7 Thanks 0 0 NULL
akash 3 10 0 0 NULL
I Need the output as:
first_name question_id answer_id answer_text answer_rate answer_nps opt
RM 1 1 5 NULL NULL
Y 1 3 0 NULL NULL
Ben 1 5 0 NULL NULL
akash 1 8 2.5 NULL NULL
RM 2 2 0 4 NULL
Y 2 4 0 3 NULL
Ben 2 6 0 0 NULL
akash 2 9 0 0 NULL
RM 3 NULL 0 0 NULL
Y 3 NULL 0 0 NULL
Ben 3 NULL ThankS 0 0 NULL
akash 3 NULL 0 0 NULL
Where in third and fourth row from last doesnt have the id 3 but i need to replace as 3 and other values in that two rows has to be null

Answer 1

What you want to do is rather complicated. You want a row for each responder and question, and then to fill in the details for those that responded. My guess is that you want the answer_id filled in, where available. That is, your desired results should have answer_ids for "Ben" and "Akash".
The following query generates all the rows using a cross join between the responders and the questions. Then it brings in the additional information:
SELECT r.respondant_firstname as first_name, q.question_id as question_id,
a.answer_id, a.answer_text, a.answer_rate, a.answer_nps,
qr.question_radio_text as opt
FROM respondant r CROSS JOIN
question q LEFT JOIN
answer a
on a.answer_question_id = q.question_id and
a.answer_respondant_id = r.respondant_id LEFT JOIN
question_radio qr
on a.answer_question_radio_id = qr.question_radio_id
WHERE q.question_feedback_id = 1
ORDER BY q.question_id, a.answer_id;