our $lname;
our $fname;
our $title;
our $eid;
our $supervisor;
our $supervisor2;
our $supervisor3;
our $supervisor4;
our $supervisor5;
our $supervisor6;
our $supervisor7;
our $supervisor8;
		
#select fname, lname, csg from acnse where supervisor ='pierre.nanterme';
my $sth = $dbh->prepare("SELECT fname, lname, title, supervisor FROM acnse WHERE eid ='employeID';");
$sth->execute or die $sth->errstr;

my $row=23;

while ( my $aref = $sth ->fetchrow_arrayref)
   {
   $supervisor2 = add_aref_to_sheet($aref, $worksheet0);

   my $sth = $dbh->prepare("SELECT fname, lname, title, supervisor FROM acnse WHERE eid ='$supervisor2';");
   $sth->execute or die $sth->errstr;

   while ( my $aref = $sth ->fetchrow_arrayref)
      {
      $supervisor3 = add_aref_to_sheet($aref, $worksheet0);

      my $sth = $dbh->prepare("SELECT fname, lname, title, supervisor FROM acnse WHERE eid ='$supervisor3';");
      $sth->execute or die $sth->errstr;
			
      while ( my $aref = $sth ->fetchrow_arrayref)
         {
         $supervisor4 = ....
         ... continue for several more levels ...
         }
      }
   }

sub aref {
   ... same as shown earlier ...
}