PHP OOP 与 MySQL

Question

好吧，伙计们遇到了大麻烦，无法理解正在发生的事情。 请帮忙。

首先我有一个数据库连接类:

    private $localhost = DB_LOCALHOST;
    private $db = DB_DATABASE;
    private $user = DB_USER;
    private $password = DB_PASSWORD;
    protected $link ;


    function __construct()
      {

       $this->link = mysql_connect($this->localhost,$this->user,$this->password) or die(mysql_error()."<br/>".mysql_errno());
       mysql_query("SET NAMES ".DB_CHARSET , $this->link) or die(mysql_error()."<br/>".mysql_errno());
       mysql_select_db($this->db, $this->link)or die(mysql_error()."<br/>".mysql_errno());
           if($this->link===false)
           die("Didn't connect to DB");            

       }

       function sql_query($q)
       {    
          $r = mysql_query($q, $this->link) or die ("DATABASE ERROR! Please, contact the administrator.".mysql_error().);
          return $r;
       }

        function __destruct()
        {
           mysql_close($this->link);
        }

      }

然后我在另一个函数中使用它的两个不同功能:

     function del_meal($id_meal)
     {
         $db_s = new DBConnect();
     $db_s->sql_query("DELETE FROM `pictures` WHERE `id_target` = '{$id_meal}' AND `type` = 'meal';");
     $db_s->sql_query("DELETE FROM `meal_ingredient` WHERE `id_meal` = '{$id_meal}';"); 
     $db_s->sql_query("DELETE FROM `meal` WHERE `id_meal` = '{$id_meal}';"); 
     unset($db_s);
     $pictures = $this->select_pictures($id_meal,'meal');
         if(count($pictures)>0)
         {
           foreach($pictures as $pic)
           {
            if(file_exists("./pictures/meal/{$pic}"))
             {
               unlink("./pictures/meal/{$pic}");
               unlink("./pictures/meal/thumb/{$pic}");
             }
           }
         }
     }

    function del_category($id_category)
    {
       $db = new DBConnect();
       $id_category = $db->safe_var($id_category);
       $q = $db->sql_query("SELECT * FROM `meal` WHERE `id_category` ='{$id_category}' ");
    while($res = mysql_fetch_assoc($q))
    {
        $this->del_meal($res['id_meal']);
    }
    $db->sql_query("DELETE FROM `meal_category` WHERE `id_category` = '{$id_category}' ");
    unset($db);
    }

好的 - 这是 safe_var()

   function safe_var($var)
  {
      $var = stripslashes($var);
      $var = trim($var);
      $var = strip_tags($var);
      $var = mysql_real_escape_string($var);
      $var = htmlspecialchars($var);
      $var = nl2br($var);

      return $var;
  }

所以 - 当我只使用 del meal 功能时 - 一切都很好 - 但当我使用 del category - 我在第 33 行的 DBConnect.php 中收到“警告:mysql_query(): 7 不是有效的 MySQL-Link 资源 数据库错误!请联系管理员。”

可能是什么原因。有人可以帮助我吗？

Answer 1

正如 SkippyChalmers 所说，您需要一个数据库实例。

function db($config)
{
    static $db = NULL;
    if($db === NULL)
    {
        $db = new DBConnect($config);
    }
    return $db;
}

// db()->sql_query(...);

但是，我建议you switch to PDO .