PHP empty field validation

Question

I have a enrollment form where users have to input there address. I am using PHP for validation and currently I check to make sure the field is not empty. Here is my code:

Answer 1

if($_POST['submit']){
    $address = $_POST['address'];

    if (empty($address)) {
        echo "You must enter an address";
    } else {
        $address = mysqli_real_escape_string($dbc, strip_tags($user_address)) ;
    }
}

You can echo immediately the message if the field address is empty

also the $_POST['submit'] is to determine if the user click the submit button