hiberante入门（十二）：继承关系2

<class name="Employee" discriminator-value="0"><id name="id"><generator /></id><discriminator column="sign" type="string" /><property name="name"></property><many-to-one name="depart" column="depart_id" /><subclass name="Sale" discriminator-value="1"><property name="signSale"></property></subclass><subclass name="Skill" discriminator-value="2"><join table="skill"><key column="skill_id" /><property name="signSkill" /></join></subclass></class>
<class name="Employee"><id name="id"><generator /></id><property name="name"></property><many-to-one name="depart" column="depart_id" /><union-subclass name="Sale"><property name="signSale" /></union-subclass><union-subclass name="Skill"><property name="signSkill" /></union-subclass></class>