Database connect undefined - php

Question

I'm getting an error saying Undefined variable: con,
the connection of the database is on the other php file, (include() is already on top of the code). I just don't know how to call the $con
if (isset($_POST['update_profile']))
{
if (isset($_POST['first_name']))
{
$first_name = mysqli_real_escape_string($con, $_POST['first_name']);
$sql = mysqli_query($con, "UPDATE tbl_fbusers SET fname = '$first_name' WHERE email = '$email_to_connect'");
}
if (isset($_POST['last_name']))
{
$last_name = mysqli_real_escape_string($con, $_POST['last_name']);
$sql = mysqli_query($con, "UPDATE tbl_fbusers SET lname = '$last_name' WHERE email = '$email_to_connect'");
}
if (isset($_POST['contact']))
{
$contact = mysqli_real_escape_string($con, $_POST['contact']);
$sql = mysqli_query($con, "UPDATE tbl_fbusers SET contact = '$contact' WHERE email = '$email_to_connect'");
}
}
here is the other php file
class Users {
public $table_name = 'tbl_fbusers';
function __construct(){
//database configuration
$dbServer = 'localhost'; //Define database server host
$dbUsername = 'root'; //Define database username
$dbPassword = ''; //Define database password
$dbName = 'db_zalian'; //Define database name
//connect databse
$con = mysqli_connect($dbServer,$dbUsername,$dbPassword,$dbName);
if(mysqli_connect_errno()){
die("Failed to connect with MySQL: ".mysqli_connect_error());
}else{
$this->connect = $con;
}
}
Thanks!

Answer 1

Defining $con as a GLOBAL variable is a terrible idea...
I suggest to make a file (eg. connection.php) that will contain the $con variable that is not in a function, and then include the connection.php to your other php files. It's more secure and easier, and you won't get to any troubles.

Answer 2

Since you have a class you need to initialize user class.
$user = new Users();
and then
$con = $user->connect;
Here you can run your sql like:
$contact = mysqli_real_escape_string($con, $_POST['contact']);
$sql = mysqli_query($con, "UPDATE tbl_fbusers SET contact =......... etc.

Answer 3

you need to define $con as global:
global $con
$con = mysqli_connect($dbServer,$dbUsername,$dbPassword,$dbName);