在同一查询中使用INNER JOIN两次 - Using INNER JOIN twice in the same query

Using INNER JOIN twice in the same query

本文关键字：INNER JOIN 两次查询 | 更新日期: 2023-09-27

我仍在努力掌握SQL的窍门。我构建了一个查询，从filter_thread（包含"filter_id"answers"thread_id"列）表和filter（"filter__id"answers"tag"）表的中提取thread_ids

然后，我使用一个完全不同的查询来查找线程表内容，其中包含"thread_id"

我意识到这不是最好的方法，但无法获得成功的查询。有人能帮忙吗？

$query = "SELECT ft0.thread_id 
FROM filter f0 
INNER JOIN filter_thread ft0 ON ft0.filter_id = f0.filter_id 
WHERE f0.tag LIKE '%filter1%' 
OR f0.tag LIKE '%filter2%'"
$result = $query->result_array();
$thread = array();
foreach ($result as $thread_id)
{
   $id = $thread_id['thread_id'];
   $query = $this->db->query("SELECT * FROM thread WHERE thread_id='$id'");
   $thisRow = $query->result_array();
   array_push($thread, $thisRow[0] );
}

谢谢！

您可以在单个查询中完成，如下所示：

SELECT t.*
  FROM filter AS f0
 INNER JOIN filter_thread AS ft0
    ON ft0.filter_id = f0.filter_id
 INNER JOIN thread AS t
    ON ft0.thread_id = t.thread_id
 WHERE f0.tag LIKE '%filter1%'
    OR f0.tag LIKE '%filter2%

select t.x, t.y, ... from thread t
inner join filter f on f.thread_id = t.thread_id
inner join filter_thread ft on ft.filter_id = f.filter_id
where bla bla

也许有人在旁边。。。？

试试这个

SELECT t.*, f0.*
FROM filter f0 
INNER JOIN filter_thread ft0 ON ft0.filter_id = f0.filter_id 
INNER JOIN thread t ON t.thread_id = ft0.thread_id 
WHERE f0.tag LIKE '%filter1%' 
OR f0.tag LIKE '%filter2%'"
GROUP BY f0.filter_id