PHP数据库操作单例类

function MysqlOnce{private $con;static private $_instance;private function __construct($host,$username,$password,$db){$this -> con = @mysql_connection($host,$username,$password);@mysql_select_db($db,$this -> con);@mysql_query("set name 'utf-8'", $this -> con);return $this -> con;}private function __clone(){}public static function once_mysql($host,$username,$password,$db){if(false == (self::$_instance instanceof self)){self::$_instance = new MysqlOnce($host,$username,$password,$db);}return $_instance}public function select($sql){$sql = "select * from table";$query = mysql_query($sql);$list[] = mysql_fetch_assoc($query,$this -> con);return $list;}}