按外键的表列排序表

Question

我有一个带有 post_id 外键的 cmets 表，用于帖子表。 cmets 表有likes/dislikes 列。如何按comments table DESC 中的likes 或dislikes 的编号订购posts？

cmets 和帖子是分开加载的。 cmets API 运行良好并相应地对 cme​​ts 进行排序（最喜欢/最不喜欢），但是在显示帖子时，我通过 posts.comments DESC 对它们进行排序，因为我没有解决方法

<?

switch ($orderReactions) {
  case "pdt":
    if ($orderTags == "alltags") {

      $orderBy = "WHERE users.id = posts.user_id ORDER BY posts.posted_at";
    }else {
      $orderBy = "WHERE users.id = posts.user_id AND tags=:tag ORDER BY posts.posted_at";
    }
    
    break;
  case "mlp":
    if ($orderTags == "alltags") {

      $orderBy = "WHERE users.id = posts.user_id AND posts.likes != 0 ORDER BY posts.likes";
    }else {
      $orderBy = "WHERE users.id = posts.user_id AND tags=:tag AND posts.likes != 0 ORDER BY posts.likes";
    }
    
    break;
  case "mdp":
    if ($orderTags == "alltags") {

      $orderBy = "WHERE users.id = posts.user_id AND posts.dislikes != 0 ORDER BY posts.dislikes";
    }else {
      $orderBy = "WHERE users.id = posts.user_id AND tags=:tag AND posts.dislikes != 0 ORDER BY posts.dislikes";
    }
    
    break;
  case "mcp":
    if ($orderTags == "alltags") {

      $orderBy = "WHERE users.id = posts.user_id AND posts.comments != 0 ORDER BY posts.comments";
    }else {
      $orderBy = "WHERE users.id = posts.user_id AND tags=:tag AND posts.comments != 0 ORDER BY posts.comments";
    }
    
    break;
  case "mlc":
    if ($orderTags == "alltags") {

      $orderBy = "INNER JOIN comments ON comments.post_id = posts.id WHERE posts.user_id = users.id AND posts.comments != 0 AND comments.likes != 0 GROUP BY post_id ORDER BY comments.likes";
    }else {
      $orderBy = "INNER JOIN comments ON comments.post_id = posts.id WHERE posts.user_id = users.id AND tags=:tag AND posts.comments != 0 AND comments.likes != 0 GROUP BY post_id ORDER BY comments.likes";
    }
    
    break;
  case "mdc":
    if ($orderTags == "alltags") {

      $orderBy = "INNER JOIN comments ON comments.post_id = posts.id WHERE posts.user_id = users.id AND posts.comments != 0 AND comments.dislikes != 0 GROUP BY post_id ORDER BY comments.dislikes";
    }else {
      $orderBy = "INNER JOIN comments ON comments.post_id = posts.id WHERE posts.user_id = users.id AND tags=:tag AND posts.comments != 0 AND comments.dislikes != 0 GROUP BY post_id ORDER BY comments.dislikes";
    }
    
    break;
  default:
    if ($orderTags == "alltags") {

      $orderBy = "WHERE users.id = posts.user_id ORDER BY posts.posted_at";
    }else {
      $orderBy = "WHERE users.id = posts.user_id AND tags=:tag ORDER BY posts.posted_at";
    }
    break;
}

//posts from users followed by current logged in user + logged in user
if ($orderTags == "alltags") {

  $followingposts = $db->query('SELECT posts.id, posts.body, posts.posted_at, posts.likes, posts.dislikes, posts.tags, posts.user_id, users.`username`, users.`profileimg` FROM users, posts
    '.$orderBy.' DESC LIMIT 10 OFFSET '.$start.';');
  
}else {

  $followingposts = $db->query('SELECT posts.id, posts.body, posts.posted_at, posts.likes, posts.dislikes, posts.tags, posts.user_id, users.`username`, users.`profileimg` FROM users, posts
    '.$orderBy.' DESC LIMIT 10 OFFSET '.$start.';', array(':tag'=>$orderTags));

}

?>

更新

代码已更新以反映我添加的 INNER JOIN 解决了我的问题

Answer 1

我假设您正在编写一个类似于 Stack Overflow 的网站，其中您有多个 cmets（答案）并且每个都可以有喜欢和不喜欢（上下投票）。

我认为你能做的最好的事情就是把所有这些都组装成一个存储过程。从那里你可以传入一个参数来确定排序。至于您遇到的实际问题，您可以从 cmets 表对帖子表进行内部连接，然后您可以简单地说按 cmets.likes 和 cmets.dislikes 排序。

以下是 mssql 服务器的正确语法，但我确信可以轻松转换为 mysql。

CREATE PROCEDURE spGetPostsByNumberOfComments @OrderByType VARCHAR(50)
AS
 BEGIN
     SELECT *
     FROM Posts
          INNER JOIN Comments ON Comments.PostId = Posts.PostId
    ORDER BY
        CASE WHEN @OrderByType = 'CommentLikes' THEN Comments.Likes
        WHEN @OrderByType = 'CommentDislikes' THEN Comments.dislikes 
        WHEN @OrderByType= 'PostLikes' THEN Posts.likes
        WHEN @OrderByType= 'PostDislikes' THEN Posts.dislikes
        ELSE Posts.PostId
        END DESC
 END;