ALTER TABLE cars ADD COLUMN user_id INT NULL;
-- We use SET NULL so if a user is deleted, their car listings remain (maybe owned by admin)
ALTER TABLE cars ADD CONSTRAINT fk_cars_user FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE SET NULL;

ALTER TABLE bookings ADD COLUMN bank_province VARCHAR(100) NULL;
ALTER TABLE bookings ADD COLUMN bank_account_number VARCHAR(100) NULL;
ALTER TABLE bookings ADD COLUMN sale_price DECIMAL(10, 2) NULL;