CREATE SEQUENCE asset_seq;
 CREATE TABLE assets (
     asset_id integer not null default nextval('asset_seq'),
     desk     text    not null,
     status   text    not null,
     priority text    not null,
     deadline date    not null
 );

 CREATE TABLE documentasset (
     doc_id integer not null unique,
     label  text    not null
 ) INHERITS (assets);

 CREATE TABLE mediaasset (
     media_id integer not null unique
 ) INHERITS (assets);