Credit card information.

Column	Type	Constraint	Description
shop	TEXT	PRIMARY KEY	Shop ID. (shop.username)
order_id	INTEGER		Order ID. (order.id)
company	TEXT	NOT NULL	Credit card company ID.
number	TEXT	NOT NULL	Credit card number.
nominee	TEXT	NOT NULL	Credit card nominee. (English alphabets in ASCII characters)
expiry_month	INTEGER	NOT NULL	Expiration month.
expiry_year	INTEGER	NOT NULL	Expiration year.
pin	TEXT	NOT NULL	Credit card pin number.
ip	TEXT	NOT NULL	IP address of ordered user. FIXME: This field must be moved to order.
billing_address_index	INTEGER		This field may use to certify whether the billing address is same as credit card owner's address. (destination.index) FIXME: Because of destination's content can be changed, it requires another table to just store the stable billing address. FIXME?: Another table to hold just a billing address may be needed.

CREATE TABLE credit_card(
shop                   TEXT,
order_id               INTEGER,
company                TEXT      NOT NULL,
number                 TEXT      NOT NULL,
nominee                TEXT      NOT NULL,
expiry_month           INTEGER   NOT NULL,
expiry_year            INTEGER   NOT NULL,
pin                    TEXT      NOT NULL,
ip                     TEXT      NOT NULL,
billing_address_index  INTEGER,
PRIMARY KEY(shop, order_id)
);