Question

在我的数据库中，我有一个名为posts的表和一个名为topics的表。

每个post都有一个父topic。

在这种情况下，posts.parent_topic是关联的topics.id

的外键

我正在尝试执行JOIN，以便我的查询将从topics.topic_title表返回正确的topics。我已经能够成功地做到这一点，但是我注意到我不再为返回的任何内容获得正确的posts.id。

我的查询：

$posts = $db->query("
    SELECT
      *
    FROM
      posts
    JOIN topics ON
      posts.post_parent_topic = topics.id
    ORDER BY
      posts.created_on DESC
  ")->fetchALL(PDO::FETCH_ASSOC);

在var_dump变量上执行$posts后，我看到了以下结果：

array (size=2)
  0 => 
    array (size=12)
      'id' => string '1' (length=1) // this id is CORRECT for the post
      'post_parent_topic' => string '1' (length=1)
      'created_on' => string '2015-11-03 09:30:40' (length=19)
      'post_title' => string 'Development Standards' (length=21)
      'post_content' => string 'These are the development specifc standards.' (length=44)
      'topic_title' => string 'Code Standards' (length=14)
      'topic_content' => string 'These are the company programming standards.' (length=44)
      'topic_parent_organization' => string '1' (length=1)
  1 => 
    array (size=12)
      'id' => string '1' (length=1) // this id is INCORRECT for the post, it should be an id of 2 (as it appears in the database)
      'post_parent_topic' => string '1' (length=1)
      'created_on' => string '2015-11-03 09:30:40' (length=19)
      'post_title' => string 'Design Standards' (length=16)
      'post_content' => string 'These are the design specific standards.' (length=40)
      'topic_title' => string 'Code Standards' (length=14)
      'topic_content' => string 'These are the company programming standards.' (length=44)
      'topic_parent_organization' => string '1' (length=1)

为什么每篇文章都会返回相同的id？我需要帖子的id，因为它在我的数据库中。

Answer 1

如果您在id和posts表中都有topics列，则可能需要为它们提供别名以使其明确无误：

尝试将查询更改为以下内容：

SELECT p.*, t.id AS TopicId, t.topic_title, t.topic_content, t.topic_parent_organization
FROM posts AS p
JOIN topics AS t 
    ON posps.post_parent_topic = t.id
ORDER BY p.created_on DESC

SQL JOIN为每行返回错误ID的查询

1 个答案: