无法包含connection.php文件以重用与数据库的连接

Question

I'm having some problem to include a connection file to my php page.

I have this connessione.php which receive from login.php the user and password to connect to my db:

<?php   
    $host="localhost";
    $user=$_POST["username"];
    $password= $_POST["password"];
    $database = "Park";
    $lingua=$_POST["lingua"];
    $myconn= new mysqli($host,$user,$password,$database); 

    if($myconn->connect_error){
        Header('Location: login.html');
    }else{
        Header('Location: form.html');
    }
?> 

This is my form.php that should use the connection.

<?php
    require ('connessione.php');
    $query="SELECT CodicePin from Pin";
    $res=$myconn->query($query);
    $row=$res->fetch_array(MYSQLI_NUM);
    print_r($row);
?> 

The problem is that it is unable to use $myconn established in connessione.php and when I try to login with right user/psw i'll be redirect to login.php.

However if i try to modify connessione.php like this and it execute the query without problem.

<?php   
        $host="localhost";
        $user=$_POST["username"];
        $password= $_POST["password"];
        $database = "Park";
        $lingua=$_POST["lingua"];
        $myconn= new mysqli($host,$user,$password,$database); 

        if($myconn->connect_error){
            Header('Location: login.html');
        }else{
        $query="SELECT CodicePin from Pin";
        $res=$myconn->query($query);
        $row=$res->fetch_array(MYSQLI_NUM);
        print_r($row);
        }
    ?> 

How i can use the same connection established by connessione.php in other php page? Thanks, and sorry about my english :)

Answer 1

In Connection Page, i named DbConfig.php

 // DB connection
    $host="localhost"; // Host name
    $username="root"; // Mysql username
    $password=""; // Mysql password
    $db_name="demoproject"; // Database name

    // Connect to server and select databse.
    $con=mysqli_connect("$host", "$username", "$password","$db_name") or die("cannot connect");
if(mysqli_connect_errno()){
    echo "Failed to Connect Database: ". mysqli_connect_error();
//You can redirect here
    exit();
}

in Process Page

require_once("DbConfig.php");

$sql="SELECT CodicePin from Pin";
$result=mysqli_query($con,$sql);
$row=mysqli_fetch_array($result);
var_dump($row);