select distinct top_no from top WHERE rownum < 5

$sth = $oDbh->prepare($query);
$sth->execute();

while ( my $rowUpper = $sth->fetchrow_hashref)
{
 my $query = "select file.* where top_no = '". $rowUpper->{top_no}."'";

 <> Here its not working since it is printing TOP_NO i.e. in caps
}

Printed with the Data::Dumper and it is printing this

$VAR1 = [
          {
            'TOP_NO' => '072B03'
          }
        ];