# get the first relationship
    my $firstrel = shift @{$refs->{related}};
    
    # compose some sql
    my $sql = qq{
        SELECT * FROM $refs->{table} AS $refs->{alias}
        JOIN $firstrel->{name} AS $firstrel->{alias}
          ON }
        .
        join (' AND ', @{$firstrel->{joins}});

    print $sql; 
    __END__

    output:
    
    SELECT * FROM this_table AS tt
      JOIN other_table AS ot
        ON tt.person_id = ot.person_id
       AND tt.week_id = ot.week_id