Btukfyl

I'm building a website and I'd like to limit how many users can register on it.

As you can see from the photo, I have a db in phpMyAdmin called website with two tables in it. One for the codes that I create and one for store the registered users.
I'd have a normal register html form with a field for 'CODE'. I 'd like to stop the user from registering if the code doesn't exist or doesn't match the codes I have in the table. After they register I'd like the code to be deleted from the table but I can't figgure out how to do it. This is my code in
HTML

<form class="login-form" method="POST" action="#">

        <input type="text" name="username" required="required">

        <input type="password" name ="password" required="required">

        <input type="text" name="code" required="required">

        <input type="submit" value="Register">

</form>

PHP

<?php

$host = "192.168.11.32:3306";

$user = "cyka";

$password = "blyat";

$db = "website";

$conn = mysqli_connect($host, $user, $password, $db);



if(isset($_POST['code'])){

    $userCode = $_POST['code'];

    $userUsername = $_POST['username'];

    $userPassword = $_POST['password'];

    $sql = "SELECT * FROM codes WHERE codice = '$userCode'";

    $result = mysqli_query($conn, $sql);



    if(mysqli_num_rows($result)==1){

        $sql = "INSERT INTO users (username, password) VALUES ('$username', '$password')";

        if ($conn->query($sql) === TRUE) {

            echo "Thank you for registering!";

        } else {

            echo "Errore: " . $sql . "<br>" . $conn->error;

            }

        header('location: main.php');

    } else {

        echo ("The code is not valid!");

        header('location: error.php');

    }

} 

?>

Submit the form via an ajax request upon hitting 'register' on your form.

Example of an ajax request to a back-end file:

$('#register-form').submit( function(e){

        e.preventDefault();

        $.ajax({

            url : '/includes/register.php',

            type : "POST",

            data : $('#register-form').serialize(),

            success : function(data) {

                if (data == 'true') {

                    //code if successful

                } else {

                    // code if not successful

                    }

                }

            }

        });



    });

All the values in the form will be posted to back-end file.

You can access the 'code' value that they have entered like this:

$theirCode = $_POST['code'];

Get an array of all your codes in your database - You can write a simple select all function:

function getCodes() {

    global $db;

        try {

        $stmt = $db->prepare("SELECT * FROM codes");

        $stmt->execute();

        return $stmt->fetchall();

    } catch (Exception $e) {

        echo $e->getMessage();

    }

}



$myCodes = getcodes();

All that you need to do now is just loop through your array of codes and check if their code matches with a code in your array.

$match = false;

foreach($myCodes as $code){

    if($theirCode == $code){

        $match = true;

        break;

    } 

}



if($match == true){

    echo 'true';

} else {

    echo 'false';

}

Your ajax request will be listening for true/false. Handel the outcome as you wish.

I do my explanation makes sense and is of help. Thanks