Untitled

<!DOCTYPE html>
<html>
<head>
    <title>Form submission</title>
</head>
<body>
<div class="content">
    <form action="SD.php" method="POST">
        <label>Name: </label><br>
        <input name="fullname" type="text" size="35"/><br>

        <label>ID: </label><br>
        <input name="ID" type="text" size="35" /><br>

        <label>email: </label><br>
        <input name="email" type="text" size="35" /><br>

        <label>Phone number: </label><br>
        <input name="phonenummber" type="text" size="35" /><br>

        <label>message: </label><br>
        <input name="message" type="text" size="65" /><br>

        <input name="mySubmit" type="submit" value="Submit!" /><br>
    </form>

</div>
</body>
</html>
<?php

$servername = "localhost";
$username = "root";
$password = "";
$dbname = "firstform";
$db = mysqli_connect('localhost','root','','firstform');

if ($db)
    echo '<br>successfully connected<br>';
//Send Data
if(isset($_POST['ID']) && isset($_POST['fullname']) &&  isset($_POST['email']) && isset($_POST['phonenummber']) && isset($_POST['message'])) {
    $myID = $_POST['ID'];
    $myName = $_POST['fullname'];
    $myMail = $_POST['email'];
    $myNummer = $_POST['phonenummber'];
    $message = $_POST['message'];
    $age = 5;
    $sql = "INSERT INTO cdb VALUES ('" . $myID. "', '".$myName."', '" . $age . "', '".$myMail."', '".$myNummer."', '".$message."')";
    $chk = $db->query($sql);
    $db->close();
    var_dump($chk);
    echo mysqli_error($db);
    echo "Submitted!";
}
?>