封装sql语句的实现思路

$userDB->email = "lee@163.com";
$userDB->address = "xxxx";
$userDB->save();
//=======或者========
$data=array("email" => "lee@163.com", "address" = "xxxx");
$userDB->save($data);

class UserDB extends DB
{
    const INSERT_SQL = "insert into users(email, address) valus(?, ?)";
    private $_data; //接收分别添加的字段
    private $_fields = array(‘email‘, ‘address‘); //过滤白名单

    public function save($data = array())
    {
        $insertData = empty($data) ? $this->_data : $data;
        $this->db->query(self::INSERT_SQL, $insertData);
    }

    public function __set($key, $value)
    {
        if (!in_array($key, $this->_fields)) {
            throw new InvalidArgumentException("$key is not allow");
        }
        $this->_data[$key] = $value;
    }
}