mysql - 在mysql查询中使用两个内连接

Question

我有两个表格，如下图所示:

用户表:

offer_comments

offer_comments 表存储评论和评论的答案。通过使用下面的函数，我可以根据 $id 获取评论并回答评论。

function getCommentsAnItem($id){

    mysql_query("SET CHARACTER SET utf8");
    $result_comments = mysql_query("select e.comment as comment,m.comment as answer_to_comment 
    from offer_comments e 
    inner join offer_comments m on e.id = m.quet 
    where e.offer_id=$id and e.confirm=1");
    $comments = array();
    while($a_comment=mysql_fetch_object($result_comments)){

        $comment = array(
        'comment'=>$a_comment->comment,
        'answer'=>$a_comment->answer_to_comment
        );
        array_push($comments,$comment);
    }

    return $comments ;
}

现在，我想使用内连接而不是 offer_comments，我该怎么办？我想使用下面的 sql 而不是 offer_comments :

select offer.*,u.id,u.name,u.family from offer_comments offer
        inner join users u on offer.id=u.id

喜欢:

    $result_comments = mysql_query("select e.comment as comment,m.comment as answer_to_comment 
    from (select offer.*,u.name,u.family from offer_comments offer
    inner join users u on offer.id=u.id) e 
    inner join offer_comments m on e.id = m.quet 
    where e.offer_id=$id and e.confirm=1");

但它返回[]!!

Answer 1

试试这个:

   $result_comments = mysql_query("select e.comment as comment,m.comment as answer_to_comment 
    from (select offer.*,u.name,u.family from offer_comments offer
    inner join users u on offer.user_id=u.id) e 
    inner join offer_comments m on e.id = m.quet 
    where e.offer_id=$id and e.confirm=1");

此处的更改是在 e 派生表中，users 和 offer_comments 之间的关系应为 users.id = Offer_comments。 user_id 并且您已完成users.id = Offer_comments.id