$store = qq-INSERT INTO main (creator_name,relationship) VALUES(?, ?)-;
my $sth = $dbh->prepare($store);
for my $i (0..3) {
  $sth->execute($data{creatorname}, $data{"relationship$i"});

  # or a nicer syntax using a hash slice:
  # $sth->execute( @data{ "creatorname", "relationship$i" } );
}