<?php
session_start();
class Lib
{
    private $host = "localhost"; // your host name
    private $username = "root"; // your user name
    private $password = ""; // your password
    private $db = "db_apti"; // your database name
    public $conn = '';
public function __construct()
{
    $conn = mysqli_connect($this->host, $this->username, $this->password,$this->db) or die(mysqli_connect_error());

}

protected function query_executed($sql)
{
    $c = mysqli_query($this->conn,$sql);
    return $c;
}

public function get_rows($fields, $id = NULL, $tablename = NULL)
{
    $cn = !empty($id) ? " WHERE $id " : " ";
    $fields = !empty($fields) ? $fields : " * ";
    $sql = "SELECT $fields FROM $tablename $cn";
    $results = $this->query_executed($sql);
    $rows = $this->get_fetch_data($results);
    return $rows;
}

protected function get_fetch_data($r)
{
    $array = array();
    while ($rows = mysqli_fetch_assoc($r))
    {
        $array[] = $rows;
    }
    return $array;
}
}

    $lib = new Lib(); //create class object here

    ?>