create table prices (
  was text not null,
  now text not null,
  on_sale boolean not null default false
);
comment on table prices is '
  Product price in USD
';

comment on column prices.was is '
  formatted price in USD
';
comment on column prices.now is '
  formatted price in USD
';
comment on column prices.on_sale is '
  true if now price is < was price. Used to
';