查询以从每个问题的答案集中选择已回答所有问题的用户

问题描述

|| 这是MysqL表。

            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

我希望已经回答所有问题的用户 我们为每个问题预定义了一组答案。 像问题1一样可以从answer1_1，answer1_2，answer1_3得到答案      问题2可以包含answer2_1，answer2_2，answer2_3的答案 最初，我尝试过这样的查询：

            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\'
                )
            )

但随后我看到了结果，并意识到所有问题中的“与”都无法满足我的要求 但我需要那种逻辑的结果。 表结构无法更改。     

解决方法

您可以执行以下操作：

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

    ,如果您在字段

User

和

Question

上具有唯一键，则可以执行以下操作：

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

您可以将num_total_questions作为变量从应用程序传递