Php 下面的问题可以更正吗

在查询中，我需要一些帮助，我不知道我是否包含正确的GROUP BY子句，并在SELECT子句中从正确的表中选择字段：

以下是数据库表：

会话表

SessionId  SessionName
1          AAA
2          AAB

SessionId  QuestionId  QuestionContent            QuestionMarks
1          1           What is 2+2?               2
1          2           What is 4+4?               3
2          1           What is 10+10 and 11+11?   5
2          2           What is 15+15?             5
2          3           What is 20+20 and 40+40?   7

AnswerId SessionId  QuestionId Answer
1        1          1          B
2        1          2          C
3        2          1          A
4        2          1          D
5        2          2          A
6        2          3          D
7        2          3          E

问题表

SessionId  SessionName
1          AAA
2          AAB

SessionId  QuestionId  QuestionContent            QuestionMarks
1          1           What is 2+2?               2
1          2           What is 4+4?               3
2          1           What is 10+10 and 11+11?   5
2          2           What is 15+15?             5
2          3           What is 20+20 and 40+40?   7

AnswerId SessionId  QuestionId Answer
1        1          1          B
2        1          2          C
3        2          1          A
4        2          1          D
5        2          2          A
6        2          3          D
7        2          3          E

答案表

SessionId  SessionName
1          AAA
2          AAB

SessionId  QuestionId  QuestionContent            QuestionMarks
1          1           What is 2+2?               2
1          2           What is 4+4?               3
2          1           What is 10+10 and 11+11?   5
2          2           What is 15+15?             5
2          3           What is 20+20 and 40+40?   7

AnswerId SessionId  QuestionId Answer
1        1          1          B
2        1          2          C
3        2          1          A
4        2          1          D
5        2          2          A
6        2          3          D
7        2          3          E

以下是查询：

   $query = "SELECT q.SessionId, s.SessionName, q.QuestionId, q.QuestionContent, GROUP_CONCAT(DISTINCT Answer SEPARATOR '') AS Answer, q.QuestionMarks 
   FROM Session s 
   INNER JOIN Question q ON s.SessionId = q.SessionId
   JOIN Answer an ON q.QuestionId = an.QuestionId
   WHERE SessionName = "AAB"
   GROUP BY an.SessionId, an.QuestionId
   ";

我想显示属于会话“AAB”的每个问题。因此，它应该显示问题ID、问题内容、答案和问号，如下所示：

 QuestionId  QuestionContent              Answer  QuestionMarks
    1           What is 10+10 and 11+11?     AD       5
    2           What is 15+15                A        5
    3           What is 20 + 20 and 40+40?   DE       7

目前，如果我正在搜索会话“AAB”中的lets say问题，它将显示以下内容：

QuestionId  QuestionContent              Answer  QuestionMarks
    1           What is 10+10 and 11+11?     AD       5
    2           What is 15+15                A        5
    3           What is 20 + 20 and 40+40?   DE       7
    1           What is 10+10 and 11+11?     AD       5
    2           What is 15+15                A        5
    3           What is 20 + 20 and 40+40?   DE       7
    1           What is 10+10 and 11+11?     AD       5
    2           What is 15+15                A        5
    3           What is 20 + 20 and 40+40?   DE       7
    1           What is 10+10 and 11+11?     AD       5
    2           What is 15+15                A        5
    3           What is 20 + 20 and 40+40?   DE       7
    1           What is 10+10 and 11+11?     AD       5
    2           What is 15+15                A        5
    3           What is 20 + 20 and 40+40?   DE       7

---

您的答案表中有一个会话ID，看起来您在加入时错过了该ID。此外，您不应该在组中使用DISTINCT，除非您多次存储同一问题/会话的同一答案是偶然的，在这种情况下，我将解决该意外，而不是在查询中编码变通方法

SELECT q.SessionId, s.SessionName, q.QuestionId, q.QuestionContent, GROUP_CONCAT(DISTINCT Answer SEPARATOR '') AS Answer, q.QuestionMarks 
FROM Session s 
INNER JOIN Question q ON s.SessionId = q.SessionId
JOIN Answer an ON q.QuestionId = an.QuestionId
             AND an.sessionID = s.sessionID
WHERE SessionName = "AAB"
GROUP BY an.SessionId, an.QuestionId

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您没有提到您的查询应该做什么。一个你期望的结果表会有帮助。输出和期望的结果是什么？在phpmyadmin中玩比猜测更容易：）分组不能只用于聚合函数？肯定需要更好地理解a）这些数据代表什么，b）你期望从查询中得到什么行为，c）你得到什么行为。是的，很抱歉，当你们在输出上发表评论时，我更新了这个问题，我更新了问题以包含输出wantedHi，是的，我也算出了，与您的答案完全相同。我正要发布我自己的答案，但幸运的是看到了你的答案。无论如何，最好的答案是给你