$query = "SELECT stempel.oid,stempel.id,stempel.status,start,customer,time,task,kurz FROM stempel JOIN stempel_status ON (stempel.status = stempel_status.id) WHERE time IS NOT NULL ";
if (isset($month) && strlen($month))
$query = "SELECT stempel.oid,stempel.id,stempel.status,start,customer,time,task,kurz FROM stempel JOIN stempel_status ON (stempel.status = stempel_status.id) WHERE time IS NOT NULL ";