mysql联合还是加入？

Question

我有 2 个表，一个问题表和一个答案表:

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

我想要一个列表，列出所有被问及是否有答案的问题，以及所有已提供的答案。我这样做没有任何问题，但我不确定的部分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。

目前我有这个查询:

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？或者我是否需要另一种带有左连接的查询？

Answer 1

你需要的是一个join

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