PHP OOP MYSQLi Class

if($this->type == 'mysqli'){

<?php

Class DB{

   /**
   * @var object
   * Database connection
   */
   private static $connection = null;

   /**
   * @var String
   * Type of Database
   * Default MySQLi
   */
   private $type = 'mysqli';

   /**
   * @var String
   * SQL Query
   */
   private $query = '';

   private static $hostname = 'localhost';
   private static $username = 'root';
   private static $password = '';
   private static $dbname = 'fontilate';
   private static $port = 3306;

   public function __contruct(){
   
   }
   public static function getConnection(){
      if($this->type == 'mysqli'){

         $this->connection = new mysqli($this->hostname,$this->username,$this->password,$this->dbname,$this->port);
      }

      if(!$this->connection){
         echo $this->connection->connect_errno();
      }else{
         $this->connection->query('SET NAMES utf8');
         return $this->connection;
      }
   }

   /**
   * Quering SQL
   * @return result
   */

   public function sqlQuery($query){
      return $this->connection->query($query);
   }

   /**
   * Fetch Assoc
   * @var array
   */

   public function fetchAssoc($result,$type_assoc){
      switch($type_assoc){
         case 'ASSOC': $fetch = 'MYSQLI_ASSOC';
         case 'NUM': $fetch = 'MYSQLI_NUM';
      }
      $res = array();
      while($tmp = $result->fetch_array($fetch)){
         $res[] = $tmp;
      }

      return $res;
   }


   /**
   * SQL Select
   */

   public function select($select){
      $this->query = 'SELECT ' . $this->escape($select);
      return $this->query;
   }

   /**
   * SQL From
   */

   public function from($from){
      $this->query .= 'FROM ' . $this->escape($from);
      return $this->query;
   }

   /**
   * SQL Where
   */

   public function where($where){
      $this->query .= 'WHERE ' . $this->escape($where);
      return $this->query;
   }

   /**
   * SQL Limit
   */

   public function limit($limit){
      $this->query .= 'LIMIT ' . $this->escape($limit);
      return $this->query;
   }

   /**
   * Escape String - Prevent for SQL Injection
   */

   public function escape($string){
      if($this->type == 'mysqli'){
         return $this->connection->real_escape_string($string);
      }else{
         return addslashes($string);
      }
   }
}

$db = new DB();
$db->getConnection();
$result = $db->select('*')->from('users')->where('id = 10');
$fetch = $result->fetchAssoc('ASSOC');
foreach($fetch as $data){
   echo $data['name'];
}
?>

$obj = new DB();
$obj->getConnection();

DB::getConnection();

$result = $db->select('*')->from('users')->where('id = 10');