PHP signup system won't work (phpmyadmin, wampserver) - php

Question

My php signup system won't connect to my locally hosted phpmyadmin database even though I've checked through spelling errors and everything seems like it should work. The header wont change even though it's stated in the PHP sign up script. Nothing is being transferred into my database(which has no errors with it). If someone could tell me what I'm doing wrong that would be great. (P.S. footer.php and header.php are correct and included in the form)
Sign up error handlers and sign up script:
<?php
if (isset($_POST['submit'])) {
include_once 'dbh.inc.php';
$first = mysqli_real_escape_string($conn, $_POST)$_POST['first'];
$last = mysqli_real_escape_string($conn, $_POST)$_POST['last'];
$email = mysqli_real_escape_string($conn, $_POST)$_POST['email'];
$username = mysqli_real_escape_string($conn, $_POST)$_POST['username'];
$password = mysqli_real_escape_string($conn, $_POST)$_POST['password'];
//Error handlers
//Check for empty fields
if (empty($first)) || (empty($last)) || (empty($email)) ||
(empty($username)) || (empty($password)) {
header("Location: ../signup.php?signup=empty");
exit();
} else {
//Check is input characters are valid
if (!preg_match("/^[a-zA-Z]*$/", $first) || (!preg_match("/^[a-zA-
Z]*$/", $last)) {
header("Location: ../signup.php?signup=invalid");
exit();
} else {
//Check if email is valid
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
header("Location: ../signup.php?signup=empty");
exit();
} else {
$sql = "SELECT * FROM users WHERE user_username='username'";
$result = mysqli_query($conn, $sql);
$resultCheck = mysqli_num_rows($result);
if ($resultCheck > 0) {
header("Location: ../signup.php?signup=usertaken");
exit();
} else {
//Hashing the password
$hashedPassword = password_hash($password,
PASSWORD_DEFAULT);
//Insert the user into the database
$sql = "INSERT INTO users (user_first, user_last,
user_email, user_username, user_password) VALUES ('$first', '$last',
'$email', '$username' '$hashedPassword');";
mysqli_query($conn, $sql);
header("Location: ../signup.php?signup=success");
exit();
}
}
}
}
} else {
header("Location: ../signup.php");
exit();
}
Database connection:
<?php
$dbServername = "localhost";
$dbUsername = "root";
$dbPassword = "";
$dbServername = "loginsystem";
$conn = mysqli_connect($dbServername, $dbUsername, $dbPassword,
$dbServername);
Sign up form(html in a php file):
<?php include_once 'header.php';?>
<section class="main-container">
<div class="wrapper">
<h2>Sign Up</h2>
<form class="Sign" action="includes/signup.inc.php" method="POST">
<input type="text" name="first" placeholder="First Name"><br>
<input type="text" name="last" placeholder="Last Name"><br>
<input type="email" name="email" placeholder="E-mail"><br>
<input type="text" name="username" placeholder="Username"><br>
<input type="password" name="password" placeholder="Password"><br>
<button type="submit" name="">Sign Up!</button><br>
</form>
</div>
</section>
<?php include_once 'footer.php';?>
Please help if you can. It would be much appreciated. Thanks!

Answer 1

Give the name 'submit' to submit button of your HTML Signup Page:
<button type="submit" name="submit">Sign Up!</button>
Change PHP Signup Page POST:
$first = mysqli_real_escape_string($conn, $_POST['first']);
$last = mysqli_real_escape_string($conn, $_POST['last']);
$email = mysqli_real_escape_string($conn, $_POST['email']);
$username = mysqli_real_escape_string($conn, $_POST['username']);
$password = mysqli_real_escape_string($conn, $_POST['password']);
Change empty values checking of stmt to:
if ( (empty($first)) || (empty($last)) or (empty($email)) || (empty($username)) || (empty($password)) )
Change input characters validity checking if stmt to:
if ( (!preg_match("/^[a-zA-Z]*$/", $first)) || ((!preg_match("/^[a-zA-Z]*$/", $last)) ) )