<?php

$dbServername = "localhost";
$dbUsername = "root";
$dbPassword = "";
$dbName = "loginsystem";

$conn = mysqli_connect($dbServername,$dbUsername,$dbPassword,$dbName);

<?php

if(isset($_POST['submit']))
{
    include_once 'dbh.inc.php';

    $first = mysqli_real_escape_string($conn, $_POST['first']);
    $last = mysqli_real_escape_string($conn, $_POST['last']);
    $email = mysqli_real_escape_string($conn, $_POST['email']);
    $uid = mysqli_real_escape_string($conn, $_POST['uid']);
    $pwd = mysqli_real_escape_string($conn, $_POST['pwd']);

    //Error handlers
    //check for empty fields

    if(empty($first) || empty($last) || empty($email) || empty($uid) || empty($pwd)){
    header("Location: ../signup.php?signup=empty");
    exit();
    }