# 9.1.2\. 每个子类一张表(Table per subclass) 对于上例中的几个类而言，采用“每个子类一张表”的映射策略，代码如下所示： ``` <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> ``` 需要四张表。三个子类表通过主键关联到超类表(因而关系模型实际上是一对一关联)。