Message on successful database entry - php

Question

I'm trying to display a message upon a successful user registration however what I have doesn't seem to be working and just submits/refreshes the page. No message pops up even though data has successful been entered into the SQL database. Any tips or ideas?
<?php
require('php/connect.php');
if (isset($_POST['username']) && isset($_POST['password'])){
$username = $_POST['username'];
$email = $_POST['email'];
$password = $_POST['password'];
$query = "INSERT INTO `user` (username, password, email) VALUES ('$username', '$password', '$email')";
$result = mysql_query($query);
if($result){
echo $msg = "Successful Registration!";
}
}
?>
Learning PHP currently so sorry if there's a really obvious answer here!
Edit: Forgot to include echo. Just needed a second pair of eyes, sorry guys. Thanks for the tips!

Answer 1

First of all have this on consideration:
If you're getting started on PHP, please stop using mysql. It's deprecated, instead, you can use either PDO or MySQLi
As for your issue, your message is not being printed. Please make sure you echo the $msg variable:
$msg = "Successful Registration!";
echo $msg;
In mysqli a standard connection would be:
$DBConnect = new mysqli('serverName', 'userName', 'userPassword', 'dbName');
And that's it, that's all you need to start querying your database using mysqli.
For a mysql connection, try debugging it, see if there's a connection:
$connection = mysql_connect('localhost', 'userName', 'userPassword');
if (!$connection) {
die('Could not connect: ' . mysql_error());
}

Answer 2

Try to echo message
if($result)
{
echo $msg = "Successful Registration!";
}

Answer 3

<?php
echo "Successfully registered!";
?>