PHP实现的数据库封装类

 PHP学习实例，数据库封装类。

<?php
class Core{
  /*对数组进行继承*/
  static function inHerit($arr_orgin,$arr_output){
    return array_merge($arr_orgin,$arr_output);
 
  }

  /*打印错误*/
  static function throwError($errmsg){
    echo '&lt;p>error:'.$errmsg.'</p>';
    exit();
  }
}
?>
<?php
class db{
    private $result = array();
    private $connector = array();
    private $configs = array();
    private $active = 0;
    private $default_config = array(
        'dbtype' => 'mysql',
          'index' =&gt; 0,'user' =&gt; 'root', 'pwd' =&gt; '' ,'host' =&gt; 'localhost' ,'port'=&gt; 3306,'charset' =&gt; 'utf8' ,'dbname' =&gt; null
    );
   
   /*初始化*/
   public function __construct($config = array()){
     if($config) $this-&gt;connect($config);
   }

   public function __destruct(){
       foreach($this-&gt;connector as $index =&gt; $connect)
           $this-&gt;{'_'.$this-&gt;configs[$index]['dbtype'].'_close'}($connect);
           
   }

   private function _mysql_close($connect){
      mysqli_close($connect);
   }
   /*选择连接*/
   public function selectConnect($index){
        return  isset($this-&gt;connector[$index]) && (($this-&gt;active = $index) || true);
   }
   /*建立连接*/
   public function connect($config){
     (!isset($config['index'])) && $config['index'] = $this-&gt;default_config['index']++  ;