SYNOPSIS

        my $rs = $schema->resultset('CD');
        $rs->find_or_create( {
            artist => 'Massive Attack',
            title  => 'Mezzanine',
        } );

    As ResultSet subclass in Schema.pm:

        __PACKAGE__->load_namespaces(
            default_resultset_class => '+DBIx::Class::ResultSet::Void'
        );

    Or in Schema/CD.pm

        __PACKAGE__->resultset_class('DBIx::Class::ResultSet::Void');

    Or in ResultSet/CD.pm

        use base 'DBIx::Class::ResultSet::Void';

DESCRIPTION

    The API is the same as DBIx::Class::ResultSet.

    use exists instead of find unless defined wantarray.

    (Thank ribasushi to tell me count is bad)

 METHODS

      * exists

          $rs->exists( { id => 1 } );

      It works like:

          $rs->search( { id => 1 }, { rows => 1, select => [1] } )->single;

      It is a little faster than count if you don't care the real count.

      * find_or_create

      "find_or_create" in DBIx::Class::ResultSet:

          $rs->find_or_create( { id => 1, name => 'A' } );

      produces SQLs like:

          # SELECT me.id, me.name FROM item me WHERE ( me.id = ? ): '1'
          # INSERT INTO item ( id, name) VALUES ( ?, ? ): '1', 'A'

      but indeed SELECT 1 ... LIMIT 1 is performing a little better than
      me.id, me.name

      this module DBIx::Class::ResultSet::Void produces SQLs like:

          # SELECT 1 FROM item me WHERE ( me.id = ? ) LIMIT 1: '1'
          # INSERT INTO item ( id, name) VALUES ( ?, ? ): '1', 'A'

      we would delegate it DBIx::Class::ResultSet under context like:

          my $row = $rs->find_or_create( { id => 1, name => 'A' } );

      * update_or_create

      "update_or_create" in DBIx::Class::ResultSet:

          $rs->update_or_create( { id => 1, name => 'B' } );

      produces SQLs like:

          # SELECT me.id, me.name FROM item me WHERE ( me.id = ? ): '1'
          # UPDATE item SET name = ? WHERE ( id = ? ): 'B', '1'

      this module:

          # SELECT 1 FROM item me WHERE ( me.id = ? ) LIMIT 1: '1'
          # UPDATE item SET name = ? WHERE ( id = ? ): 'B', '1'

