my $comp_name = get_comp_name($hash{comp_id});

BEGIN {
 my $sth;

 sub get_comp_name {
      my $comp_name = shift;
      $sth = $dbh->prepare("select comp_name from company where comp_name = ?") unless $sth;
      my $r_name = $sth->selectrow_array($sth, undef, $comp_name);
      return $r_name;
  }
}