# 9.1.2\. 每個子類一張表(Table per subclass) 對于上例中的幾個類而言，采用“每個子類一張表”的映射策略，代碼如下所示： ``` <class name="Payment" table="PAYMENT"> <id name="id" type="long" column="PAYMENT_ID"> <generator class="native"/> </id> <property name="amount" column="AMOUNT"/> ... <joined-subclass name="CreditCardPayment" table="CREDIT_PAYMENT"> <key column="PAYMENT_ID"/> ... </joined-subclass> <joined-subclass name="CashPayment" table="CASH_PAYMENT"> <key column="PAYMENT_ID"/> <property name="creditCardType" column="CCTYPE"/> ... </joined-subclass> <joined-subclass name="ChequePayment" table="CHEQUE_PAYMENT"> <key column="PAYMENT_ID"/> ... </joined-subclass> </class> ``` 需要四張表。三個子類表通過主鍵關聯到超類表(因而關系模型實際上是一對一關聯)。