Programmer Humor

create table boolean (
  id integer primary key,
  name text not null unique
)
insert into boolean (name) values ('true');
insert into boolean (name) values ('false');
create table document (
  id integer primary key,
  name text not null unique,
  body text not null,
  is_archived not null integer,
  foreign key (is_archived) references boolean (id)
    on delete cascade
    on update no action
);

Solved.

Bonus: DBAs hate this one weird trick that can free up incredible amounts of disk space by deleting just two rows.