php - 使用 PHP/MySQL 运行 SQL 查询，然后对结果重新排序

Question

我正在尝试运行子查询，以便我可以根据搜索词出现的标签列对结果进行排序和输出。如果没有子查询，查询运行良好，但有了子查询，我得到了 'mysqli_num_rows() 需要参数 1为 mysqli_result, boolean 鉴于'错误。非常感谢任何帮助。

$sql = "SELECT * FROM (SELECT trackname, tag1, tag2, tag3, tag4, tag5, songtitle, zip_link, album_id, description, album_name, album_desc,  small_logo  FROM albums, tracks WHERE 

        (tag1 = '{$search_tag}' OR
        tag2 = '{$search_tag}' OR
        tag3 = '{$search_tag}' OR
        tag4 = '{$search_tag}' OR
        tag5 = '{$search_tag}')    AND   tracks.album_id = albums.id ) ORDER BY tag1
        ";  

}  else {
    echo '<br/>please enter a search word or phrase<br/><br/>';
    die;
}


        $result = mysqli_query ($mysqli, $sql);
        if($result === false)  { echo 'mysql error'; }
        $count=mysqli_num_rows($result);
        if ($count < 1) {echo '<span class="sorry">sorry - your search returned no results</div><br/>';}    
            else    {   while ($row = mysqli_fetch_array($result)) 
                `       {   

Answer 1

为什么使用子查询？以下似乎是您想要的查询:

SELECT trackname, tag1, tag2, tag3, tag4, tag5, songtitle, zip_link, album_id,
       description, album_name, album_desc,  small_logo
FROM albums join
     tracks
     on tracks.album_id = albums.id
WHERE '{$search_tag}' in (tag1, tag2, tag3, tag4, tag5)
ORDER BY tag1;

另请注意使用正确的 join 语法以及使用 in 来简化 where 逻辑。