MySQL 子记录

Question

好的，所以我一直在尝试从主记录中检索一组子记录。我正在制作一个简单的考试应用程序，并想从问题中检索答案。

我有以下表格：

Questions:

--------------------------------------------------
| question_id | exam_id | question               |
--------------------------------------------------
| 1           | 1       | What's 2+2?            |
--------------------------------------------------
| 2           | 1       | What's 6+5?            |
--------------------------------------------------

Answers:

--------------------------------------------------
| answer_id | question_id  | answer              |
--------------------------------------------------
| 1         | 1            | 4                   |
--------------------------------------------------
| 2         | 1            | 10                  |
--------------------------------------------------
| 3         | 2            | 11                  |
--------------------------------------------------
| 4         | 2            | 15                  |
--------------------------------------------------

I want to output:

--------------------------------------------------
| question_id | question       | answers         |
--------------------------------------------------
| 1           | What's 2+2?    | 4,10            |
--------------------------------------------------
| 2           | What's 6+5?    | 11,15           |
--------------------------------------------------

我正在尝试使用以下查询，但它没有返回任何内容：

SELECT 
    questions.question_id,
    questions.question,
    GROUP_CONCAT(answers.answer) as answers

FROM questions, answers

WHERE questions.exam_id = 1 AND answers.question_id = questions.question_id 

GROUP BY questions.question_id 

Answer 1

替换

GROUP BY questions.question_id 

通过

GROUP BY answers.question_id;