mysql - 在 db 字段下检索到不正确的数据

Question

我在下面有一个查询：

SELECT sa.StudentId, GROUP_CONCAT( DISTINCT StudentAnswer
ORDER BY StudentAnswer
SEPARATOR ',' ) AS StudentAnswer
FROM Student st
INNER JOIN Student_Answer sa ON ( st.StudentId = sa.StudentId )
INNER JOIN Student_Response sr ON ( sa.StudentId = sr.StudentId )
INNER JOIN Question q ON ( sr.QuestionId = q.QuestionId )
INNER JOIN Answer an ON q.QuestionId = an.QuestionId
LEFT JOIN Reply r ON q.ReplyId = r.ReplyId
LEFT JOIN Option_Table o ON q.OptionId = o.OptionId
WHERE q.SessionId =27
GROUP BY sa.StudentId, q.QuestionId
ORDER BY StudentAlias, q.SessionId

它输出的结果在这里：

在此处输入图像描述

现在我计划编写一个更大的查询，因此我将所有这些表都包含在FROM

但结果中的问题是StudentAnswer列。它显示学生的重复学生答案。这是不正确的，好像我通过从FROM语句中删除一些表来使查询稍微小一些，然后它显示正确的学生答案：

SELECT sa.StudentId, q.QuestionId, GROUP_CONCAT( DISTINCT StudentAnswer
ORDER BY StudentAnswer
SEPARATOR ',' ) AS StudentAnswer
FROM Student st
INNER JOIN Student_Answer sa ON ( st.StudentId = sa.StudentId )
INNER JOIN Question q ON ( sa.QuestionId = q.QuestionId )
WHERE q.SessionId =27
GROUP BY sa.StudentId, q.QuestionId
ORDER BY StudentAlias, q.SessionId

在此处输入图像描述

我的问题是，我能否StudentAnswer在第一个查询的列下获得正确的学生答案？

以下是表格列表：

学生：

StudentId (PK auto)  StudentForename  StudentSurname 
39                   Luke             McFadzen
40                   Chris            Tucker

学生回答：

StudentAnswerId (PK auto)  QuestionId (FK Question)  StudentAnswer  StudentId (FK student)
1                          72                         D             39
2                          73                         B             39
3                          73                         C             39
4                          73                         D             39
5                          72                         C             40
6                          73                         A             40
7                          73                         C             40
8                          73                         E             40

学生响应：

StudentResponseId (PK auto)  QuestionId (FK Question) ResponseTime  StudentId (FK student)
1                            72                       00:00:05      39
2                            73                       00:00:15      39
3                            72                       00:00:09      40
4                            73                       00:00:26      40

问题：

QuestionId (PK auto)  QuestionNo  SessionId (FK Session) ReplyId (FK Reply) OptionId (FK Option)    
72                    1           23                     1                  3
73                    2           23                     2                  7

回答：

AnswerId (PK auto)    QuestionId (FK Question)      Answer  
1                          72                         C             
2                          73                         A             
3                          73                         C             
4                          73                         D

回复：

ReplyId (PK auto)  ReplyType
1                  Single
2                  Multiple

选项表：

ReplyId (PK auto)  ReplyType
1                  A-C
2                  A-D
3                  A-E
4                  A-F
5                  A-G
6                  A-H
7                  A-I
8                  A-J

完整查询：

SELECT
sa.StudentId, StudentAlias, StudentForename, StudentSurname, q.SessionId, q.QuestionId,
QuestionNo, QuestionContent, o.OptionType, q.NoofAnswers, 
GROUP_CONCAT( DISTINCT Answer ORDER BY Answer SEPARATOR ',' ) AS Answer, r.ReplyType, QuestionMarks, 
GROUP_CONCAT(DISTINCT StudentAnswer ORDER BY StudentAnswer SEPARATOR ',') AS StudentAnswer, ResponseTime, MouseClick, StudentMark
FROM Student st
INNER JOIN Student_Answer sa ON (st.StudentId = sa.StudentId)
INNER JOIN Student_Response sr ON (sa.StudentId = sr.StudentId)
INNER JOIN Question q ON (sr.QuestionId = q.QuestionId)
INNER JOIN Answer an ON q.QuestionId = an.QuestionId
LEFT JOIN Reply r ON q.ReplyId = r.ReplyId
LEFT JOIN Option_Table o ON q.OptionId = o.OptionId
WHERE q.SessionId =27
GROUP BY sa.StudentId, q.QuestionId
ORDER BY StudentAlias, q.SessionId


Student - Student_Answer (StudentId)
Student - Student_Response (StudentId)
Student_Answer - Question (QuestionId)
Student_Response - Question (QuestionId)
Question - Answer (QuestionId)
Question - Reply (ReplyId)
Question - Option_Table (OptionId)

score 0 · Accepted Answer

实际上你的查询已经在工作了，你只需要添加这个条件

SELECT  sa.StudentId
    ,   StudentForename
    ,   StudentSurname
    ,   q.SessionId
    ,   q.QuestionId
    ,   QuestionNo
    ,   o.OptionType
    ,   GROUP_CONCAT(DISTINCT Answer ORDER BY Answer SEPARATOR ',') AS Answer
    ,   r.ReplyType
    ,   GROUP_CONCAT(DISTINCT StudentAnswer ORDER BY StudentAnswer SEPARATOR ',') AS StudentAnswer
    ,   ResponseTime
FROM    Student st
        INNER JOIN Student_Answer sa
            ON (st.StudentId = sa.StudentId)
        INNER JOIN Student_Response sr
            ON (sa.StudentId = sr.StudentId)
                AND sa.QuestionID = sr.QuestionID -- <<==lacking condition
        INNER JOIN Question q
            ON (sr.QuestionId = q.QuestionId)
        INNER JOIN Answer an
            ON q.QuestionId = an.QuestionId
        LEFT JOIN Reply r
            ON q.ReplyId = r.ReplyId
        LEFT JOIN Option_Table o
            ON q.OptionId = o.OptionId
GROUP   BY sa.StudentId , q.QuestionId;

或者，您可以使用子查询连接值

SELECT  DISTINCT sa.StudentId
    ,   StudentForename
    ,   StudentSurname
    ,   q.SessionId
    ,   q.QuestionId
    ,   QuestionNo
    ,   o.OptionType
    ,   an.QuestionAnswer
    ,   r.ReplyType
    ,   sa.StudentAns
    ,   ResponseTime
FROM    Student st
        INNER JOIN 
        (
            SELECT  StudentID, QuestionID,
                    GROUP_CONCAT(StudentAnswer ORDER BY StudentAnswer SEPARATOR ',') StudentAns
            FROM    Student_Answer
            GROUP   BY StudentID, QuestionID
        )sa ON (st.StudentId = sa.StudentId) 
        INNER JOIN Student_Response sr
            ON (sa.StudentId = sr.StudentId) AND sa.QuestionID = sr.QuestionID
        INNER JOIN Question q
            ON (sr.QuestionId = q.QuestionId) 
        INNER JOIN 
        (
            SELECT  QuestionID, 
                    GROUP_CONCAT(DISTINCT Answer ORDER BY Answer) QuestionAnswer
            FROM    Answer
            GROUP   BY QuestionID
        ) an
            ON q.QuestionId = an.QuestionId
        LEFT JOIN Reply r
            ON q.ReplyId = r.ReplyId
        LEFT JOIN Option_Table o
            ON q.OptionId = o.OptionId

SQLFiddle 演示

mysql - 在 db 字段下检索到不正确的数据

1 回答 1

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