package MyClass::DBI::SubClass;
use base MyClass::DBI;

__PACKAGE__->table('my_items');
__PACKAGE__->columns(All=>qw/id name qty parent/);

sub next_val {
   my $self = shift;
   my $sth = $self->db_Main->prepare(
      qq(SELECT nextval(\'my_items_id_seq\') ) );
      $sth->execute();
   my $id = $sth->fetch();
   return $id;
};

sub curr_value {
  my $self = shift;
  my $sth = $self->db_Main->prepare(
         qq(SELECT currval(\'my_items_id_seq') ));
     $sth->execute();
  my $id = $sth->fetch();
  return $id;
};

##</code><code>##

package MyClass::Items;
use 5.008008;
use strict;
use warnings;

use MyClass::DBI::SubClass;

sub addItem {
   my $self = shift;
   my %params = @_;
   return undef if(! defined($params{name}));
   return undef if(! defined($params{qty}));

   my $record = MyClass::DBI::SubClass->insert(
      {
          id => MyClass::DBI::SubClass->next_val(),
          name => $params{name},
          qty => $params{qty}
      });
   if(!defined($record)) {
      warn "Unable to create new item: ". $params{name};
      return undef;
   };
   return $record;
};

1;
__END__

##</code><code>##

my $parent = MyClass::DBI::SubClass->insert( {name=>"dad", qty=>1} );
my $child = MyClass::DBI::SubClass->insert(
   {
        name => "junior",
        qty => 1,
        parent => $parent->id
   });