Mysql联盟还是加入？

我有两张表，一张问题表和一张答案表，如下所示：

question : id, title, description, date, company_id
answers  : id, question_id, answer, date, company_id

我想要一份所有问题的清单，询问他们是否有答案，以及提供的所有答案。我这样做没有任何问题，但我不确定的是如何在答案数组中提供问题标题，因为我想显示答案与哪个问题相关

目前我有以下问题：

SELECT id, company_id, title, description, date, \'question\' as record_type 
        FROM `questions` WHERE company_id = 9
        UNION ALL 
        SELECT id, company_id, null as title, null as description, date, answer, question_id, \'answer\' as record_type 
        FROM `answers` WHERE company_id = 9
        ORDER BY date ASC

这几乎为我提供了我想要的：

[0] => Array
    (
        [id] => 63,
        [company_id] => 9
        [title] => question 1
        [description] => test
        [date] => 2013-08-09 20:50:19
        [record_type] => question
    )

[1] => Array
    (
        [id] => 58
        [company_id] => 9
        [title] => 
        [description] => 
        [answer] => This is Bobs answer
        [question_id] => 63
        [date] => 2013-08-09 20:52:16
        [record_type] => answer
    )

唯一的区别是，我想交叉引用问题表，并将问题标题添加到答案中，使其看起来像这样：

[1] => Array
    (
        [id] => 58
        [company_id] => 9
        [question_title] => question 1
        [description] => 
        [answer] => This is Bobs answer
        [question_id] => 63
        [date] => 2013-08-09 20:52:16
        [record_type] => answer
    )

---

我可以修改我的查询吗？或者我需要另一种类型的查询，可能需要左联接吗？

您需要的是联接

Select * from answers left join question on answers.question_id = question.id;

---

如果您只想要答案的问题标题并保持相同的结果集结构，则可以进行内部联接，因为您的答案总是有答案：

SELECT id, company_id, title, description, date, \'question\' as record_type 
FROM `questions` WHERE company_id = 9
UNION ALL 
SELECT a.id, a.company_id, q.title, q.description, a.date, a.answer, a.question_id, \'answer\' as record_type 
FROM `answers` a
INNER JOIN question q ON  q.id = a.question_id 
WHERE a.company_id = 9
ORDER BY a.`date` ASC

如果您想将问题和答案放在同一行，您可以：

SELECT * FROM question q LEFT JOIN answers a ON a.question_id = q.question_id
WHERE q.company_id = 9
ORDER BY q.`date` ASC

---

这很好，因为它向我展示了与答案相关的问题，但我也想要所有的问题，无论有没有答案。然后使用join而不是left join，非常感谢。第一个查询满足了我的需要。