$sth=$dbh->prepare("select data from mytable");
$sth->execute;
while ($data = $sth->fetchrow_arrayref()) {

if $data->[0],$data->[1],$data->[2] is the same as the equivalent elements from previous record then
   print $data->[4]
otherwise 
   print complete $data record

}
$sth->finish;
$dbh->disconnect;