带有子类的NamedQuery

Question

我有一个像这样的持久性模型：

@Entity
@Table(name="CMM_DT_EMPLOYEE")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "EMP_TYPE")        
public abstract class Employee {
    @Id
    protected Integer employeeId;
    ...
}

@Entity
@DiscriminatorValue(value = "FULL")
public class FullTimeEmployee extends Employee {
    protected Integer salary;
    // ...`enter code here`
}

@Entity
@DiscriminatorValue(value = "PART")
public class PartTimeEmployee extends Employee {
    protected Float hourlyWage;
}

命名查询（select c from FullTimeEmployee c）无效。它只返回一行，尽管Employee Table中有许多行用于此鉴别器类型。请帮忙。