Why can't you just do the following?

if ($form_username && $form_password && $form_name) {
  # create $SQL here
  # other stuff here
  print "Parms OK.\n";
} else {
  print "Missing one or more required value(s) for username, password 
+or name.\n";
}
[download]

I would imagine that you would also want to use place holders and qq() where appropriate as well.

--Jim