# This is defined in a common file
  $schema = {
    tables => {
      person => {
        name => { type => 'string', max_length => 40 }
      },
      address => {
        street => { type => 'string', max_length => 60 },
        city => { type => 'string', max_length => 30 },
        state => { type => 'string', max_length => 30 },
        zip => { type => 'string', max_length => 10 }
      },
      school => {
        name => { type => 'string', max_length => 30 },
        side => { type => 'string', max_length => 6 },
        num_students => { type => 'number' }
      }
    },
    relationships => {
      many_to_many => [
        [ person, school ],
        [ person, address ]
      ],
      one_to_many => [
        [ school, address ]
      ]
    }
  };

  use DBI;
  my $dbi = DBI->connect('DBI:mysql:database=bleh;host=localhost',
    'user', 'passwd');
  my $db = new SetDB($dbi, $schema);

  # ... then later in the body of the code ...

  $everyone = $db->newSet(
    tables => [person, [school, address]]); # This is subtle. See below
  while($person = $everyone->FetchNext()) {
    print "Name: " . $person->get("person.name") . "\n";
    print "School: " . $person->get("school.name") . "\n";
    print "School Street: " . $person->get("school.street") . "\n";
  }
  $east_siders = $everyone->filter("school.side = 'east'");
  $non_east_siders = $db->minus($everyone, $east_siders);
  $non_east_siders = $everyone->minus($east_siders);

  $non_east_siders = $everyone - $east_siders;  # subtraction
  $everyone2 = $non_east_siders + $east_siders; # union
  $everyone2 = $non_east_siders || $east_siders; # union
  $everyone2 = $non_east_siders && $east_siders; # intersection

  $c = $a + $b