Set up the query for this argument.
The argument sent may be found at $this->argument.
Overrides UserUid::query
public function query($group_by = FALSE) {
// Because this handler thinks it's an argument for a field on the {node}
// table, we need to make sure {tracker_user} is JOINed and use its alias
// for the WHERE clause.
$tracker_user_alias = $this->query
->ensure_table('tracker_user');
$this->query
->addWhere(0, "{$tracker_user_alias}.uid", $this->argument);
}