query to select users who has answered all questions from set of answers of each question

This is mysql table.

            User    Question    Answer
            20      1           answer1_2
            20      2           answer2_5
            20      3           answer3_1
            726     1           answer1_2
            726     2           answer2_5
            726     3           answer3_1

I want the users who has given answer of all questions and we have predefined set of answers for each question.

like Question 1 can have answers from answer1_1, answer1_2, answer1_3 Question 2 can have answers from answer2_1, answer2_2, answer2_3

Initially, I tried query like this:

            SELECT GROUP_CONCAT( DISTINCT CAST( User AS CHAR ) ) allUsers, COUNT( DISTINCT User ) totalUsers
            FROM survey
            WHERE
            (
                (
                Question =1
                AND Answer =  'answer1_2'
                )
                OR (
                Question =1
                AND Answer =  'answer1_2'
                )
                OR (
                Question =1
                AND Answer =  'answer1_3'
                )
            )
            AND (
                (
                Question =2
                AND Answer =  'answer2_1'
                )
                OR (
                Question =2
                AND Answer =  'answer2_2'
                )
                OR (
                Question =2
                AND Answer =  'answer2_3'
开发者_JAVA技巧                )
            )

but then I see the result and realize that 'AND' among all questions won't work for my requirement but I need the result with that logic.

Table structure cannot be changed.

You could do something like:

Select user, count(answer) from survey group by user having count(answer)=3

If you have a unique key on fields User and Question, then you could do something like this:

SELECT count(Question) answers_no, .... FROM survey GROUP BY User HAVING answers_no = num_total_questions

You could pass num_total_questions as a variable from application