register.php

<?php
error_reporting(0);
require "init.php";

$username = $_POST["username"];
$password = $_POST["password"];
$firstname = $_POST["firstname"];
$lastname = $_POST["lastname"];
$birthday = $_POST["birthday"];



$sql .= "INSERT INTO user_info (username, password, firstname, lastname, birthday)
	VALUES ('".$username."', '".$password."', '".$firstname."','".$lastname."', '".$birthday."' )";

if(!mysqli_query($con, $sql)){
    echo '{"message":"Unable to save the data to the database."}';
}

?>