closure_table.sql

-- reference Karwin

drop table closure;
drop table nodes;

create table nodes (
  node serial primary key,
  label varchar(32) not null
);

create table closure (
  ancestor int not null,
  descendant int not null,
  primary key (ancestor, descendant),
  foreign key (ancestor) references nodes(node) on delete cascade,
  foreign key (descendant) references nodes(node)
);