Using Abstract class and interface

MySQLDriver.php

<?php
abstract class DBCommonMethods //creating abstract class
{
    private $host;
    private $db;
    private $uid;
    private $password;
    public function __construct($host, $db, $uid, $password)
    {
        $this->host     = $host;
        $this->db       = $db;
        $this->uid      = $uid;
        $this->password = $password;
    }
}

interface DBInterface //create interface
{
    public function db_connect();
    public function insert($data);
    public function read($where);
    public function update($where);
    public function delete($where);
}

class MySQLDriver extends DBCommonMethods implements DBInterface {
 
  public function __construct($host, $db, $uid, $password) 
  { 
     parent::__construct($host, $db, $uid, $password); 
  } 
  public function db_connect() { //connect code goes here } 
  public function delete($where) { //delete code goes here } 
  public function insert($data) { //insert code goes here } 
  public function read($where) { //read code goes here } 
  public function update($where) { //update code goes here } 
}

?>

<?php $db = new MySQLDriver($host,$db,$uid,$password); ?>