CREATE TABLE account (
    id SERIAL PRIMARY KEY,
    name VARCHAR(48) UNIQUE NOT NULL,
    created TIMESTAMP NOT NULL
);

CREATE TABLE balance (
    id INT NOT NULL PRIMARY KEY,
    gold NUMERIC(16,2) NOT NULL,
    FOREIGN KEY (id) REFERENCES account (id)
);

CREATE TABLE transaction (
    id SERIAL PRIMARY KEY,
    account INT NOT NULL,
    withdrawal NUMERIC(16,2),
    deposit NUMERIC(16,2),
    timestamp TIMESTAMP NOT NULL,
    FOREIGN KEY (account) REFERENCES account (id)
);

CREATE TABLE transfer (
    id SERIAL PRIMARY KEY,
    from_id INT NOT NULL,
    to_id INT NOT NULL,
    gold NUMERIC(16,2) NOT NULL,
    timestamp TIMESTAMP NOT NULL,
    FOREIGN KEY (from_id) REFERENCES account (id),
    FOREIGN KEY (to_id) REFERENCES account (id)
);