Check if username exists using PHP PDO

Question

How do I check if a username exists using PDO? All I need to know is a bool true (exists) or false (does not). I have the initial parts set up but am unsure what to do next

$sthandler = $dbhandler->prepare('SELECT username FROM userdb WHERE username=? LIMIT 1');
$sthandler->execute(array('username'));
// ... What's next?

Answer 1

Check for the row count:

if ( $sthandler->rowCount() > 0 ) {
  // do something here
}

Answer 2

Just grab the row:

if( $row = $sthandler->fetch() ){
    // User exists: read its details here
}else{
    // User does not exist
}