Miguel Vaz <pagongski@xxxxxxxxx> wrote: > [...] > * sites (generic): > id_site > name > description > x > y > * site_natural > id > id_site > altitude > * site_arqueology > id > id_site > id_category > id_period > But i seem to be missing something. How can i have this in a way that its > easy to list only "arqueology sites" for example. I feel the solution is > simple enough, even for me, but its eluding me. Any help in the right > direction would be very appreciated. You mean archaeological sites that are not also natural sites? | SELECT * FROM site_arqeuology | WHERE id_site NOT IN | (SELECT id_site FROM site_natural); There are numerous other ways to do this, i. e., with "LEFT JOIN", "EXCEPT", etc. Tim -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
