while ( my $hashref = $query->fetchrow_hashref() ) {
    my $tmpref  = $noderef{ $$hashref{pid} }; 
#reference to the parent node
    my $cid = $$hashref{cid}; 		#CID will be used several times
    my $nodeone = Tree::DAG_Node->new(
        {
            name   => $cid, #CID as node name
            mother => $$tmpref,				#mother is the parent
        }
    );
    $noderef{ $cid }      = \$nodeone; #add this node ref to the hash
    $comm_hashref{ $cid } = $hashref; 
}