Hier eine Funktion, die genau dies erledigt:

private function fetchUsersFromJobfunction($jobfunction) {
    $sql = 'SELECT DISTINCT username FROM JRUSERJOB where jobfunction=?';
    $parameterValues = [$jobfunction];
		$parameterTypes = [JobRouter\Common\Database\ConnectionInterface::TYPE_TEXT]
    $res = $jobDB->preparedSelect($sql, $parameterValues, $parameterTypes);
    return $res;
}

Danach dann das result processing, z.B. mit einer while-Schleife:

$usersInFunctionAccounting = [];
$jobfunction = 'Accounting';
$result = fetchUsersFromJobfunction($jobfunction)

while($row = $jobDB->fetchRow($result)) {
				$usersInFunctionAccounting[] = $row['username'];
}