To have a form where people enter their email address and if that email address is already in the database at least five times they are then they're sent an email with a link?

I want people who recommend their friends and when they've recommended five people they get a bonus

Thanks

SELECT COUNT(*) AS [Count] FROM myTable WHERE emailAddress='$enteredEmailAddress'

//pull count out

if ($count > 5){

//send email

}

Brilliant thanks - do I use as is or do I change [count] to anything? Also do I add this to the page that sends the results of the form to the db? One other question, is it possible to change this so that if enterEmailAddress is the same five times it sends the email, but only if myaddress is different every time?
Thanks