查找具有多个标签的帖子

Question

我正在搜索具有多个标签的帖子并想出了以下代码，有没有更好的方法来做到这一点或者这样可以吗？

我的 MySQL 数据库有三个表 post、tags 和 post_tags

• 帖子：id|body
• 标签：标签|模式
• post_tags: postid|标签

（每个vpost上的每个标签都有自己的列）

     if(isset($_GET["query"])){
    $query = trim($_GET['query']);
    $searchs = explode(",", $query);
    $results = DB::query('SELECT * FROM post_tags WHERE tag=:tag', array(':tag' => $searchs[0]));
    $posts = "";
    foreach($results as $result){
        $pass = true;
        foreach($searchs as $search){
            if(DB::query('SELECT * FROM post_tags WHERE post_id=:postid AND 
tag=:tag', array(':postid' => $result['post_id'], ':tag' => $search))){

            }else{
                $pass = false;
                break;
            }
        }
        if($pass){
            $posts .= $result['post_id'];
        }
    }
    echo $posts;
}

我主要担心的是如果一个标签有数百万个帖子，它会不会循环数百万个听起来效率不高的东西。

编辑：

if(isset($_GET["query"])){
    $query = trim($_GET['query']);
    $searchs = explode(",", $query);
    $dataquery = "SELECT * FROM posts AS P
INNER JOIN post_tags AS PT
    ON PT.postid = P.id
INNER JOIN tags AS T
    ON PT.tag = T.tag";

    foreach($searchs as $search){
        $dataquery .= " WHERE T.tag = :tag";
    }

    $posts = DB::query($dataquery, array(':tag' => $searchs));

    echo sizeof($posts);

查询方法

     public static function query($query, $params = array()) {
    $statement = self::connect()->prepare($query);
    $statement->execute($params);
    if (explode(' ', $query)[0] == 'SELECT') {
        $data = $statement->fetchAll();
        return $data;
    }
}

Answer 1

$sql = "SELECT * FROM posts AS P
            INNER JOIN post_tags AS PT
                ON PT.postid = P.id
            INNER JOIN tags AS T
                ON PT.tag = T.tag
        WHERE " . str_repeat(" T.tag = ? AND", count($searchs));

// The actual SQL you will be using. We are removing the last ' AND' from the sql
$sql = substr($sql, 0, -4);

// The correct way
$posts = DB::query($sql, $searchs);

Answer 2

请您出示您的桌子。 或者你可以在你的表中添加关系并使用这样的查询 sql

SELECT * FROM posts p
left join post_tags pt on pt.post_id =  p.id
left join tags t on pt.tag_id = t.id
WHERE t.tag = '$searchs[0]' 

我认为像 %$searchs[0]% 这样的 t.tag 更好。如果你更多的搜索关键字，你可以使用

WHERE t.tag = '$searchs[0]' OR t.tag = '$searchs[1]'

或者你可以在帖子标题中搜索

WHERE t.tag = '$searchs[0]' OR p.post_title = '$searchs[0]'