二、假設我們有一個投資公司的資料庫包含以下屬性：B-Broker, O-Office of a broker, I-Investor, S-Stock, Q-Quantity of stock owned by an investor, D-dividend paid by a stock。整體 schema R =（B, O, I, S, Q, D）。假設此 資料庫有以下 functional dependency, I → B, IS → Q, B → O, S → D。