coding for 'no match found'

This is a simple yet fundamental programming question I am hoping somebody will have the patience to explain... I have a mysql database with the "email" field as the key. Before inserting an new record to it I want to check if there is already a record with that e-mail. This I can do fine. But this script needs to also handle delete requests, which I can also do fine, but I need to code for the instance that there is a delete request for an e-mail record that does not exist. How can I figure out if after my 'while' loop is finished checking the database it has not found a match (so i can inform the requester as such)? Here's the code I have so far... $email_check_query = "SELECT email FROM $tablename WHERE email = '$email'"; $email_check_result = mysql_query($email_check_query); while($email_query_data = mysql_fetch_array($email_check_result)) { $db_email = $email_query_data["email"]; //if match, it's an update or delete if ($email==$db_email) { if ($op=="delete") { $action="del"; echo "delete request<br>"; } else { $action = "upd"; echo "update request<br>"; } } } //end while loop ----------- providing the finest in midget technology