Deleting mysql entries with phpmyadmin leaves behind blank entries

I'm managing a mysql database with phpmyadmin and accessing it via a web application I've written in PHP. I'm entering a bunch of entries for testing, then deleting them via phpmyadmin. The problem is that when I run my queries it is returning a bunch of null rows in the result set. When I browse the database table it only shows the rows I expect (ie - the deleted rows appear to be gone). Why do these ghosts continue to haunt my db queries?

Here's the code that I'm using to return the db values:

$re开发者_如何学运维sult = $conn->query("SELECT DISTINCT username, mail, password, id FROM guest WHERE role = ? AND mailed = ?", array(2,0,));