Options:
- Disable warning messages, by editing the setting in PHP.ini
- Add an
@ sign in front of the variable name, which will suppress the error on that particular line.
- Change your code to use
isset($_POST['SUBMIT']) before checking it further.
Of these, the third option is definitely the best. You shouldn't assume that any variable supplied by the user will be set as you expect; you should always check that it's set at all, and also that it's set to the expected values. Otherwise you are liable to be open to hacking attacks.
