create table invoices (
  id integer,
  invoice_number text not null,
  po_number text not null,
  due_date date not null,
  amount_cents bigint not null,
  created_at timestamptz
);
comment on table invoices is '
  An invoice
';

comment on column invoices.id is '
  Unique identifier for an invoice
';
comment on column invoices.invoice_number is '
  The invoice number associated with the invoice
';
comment on column invoices.po_number is '
  The purchase number associated with the invoice
';
comment on column invoices.due_date is '
  When invoice payment is due
';
comment on column invoices.amount_cents is '
  Total amount of invoice in US cents
';
comment on column invoices.created_at is '
  Invoice creation timestamp
';