@Entity@DiscriminatorValue("BMW")publicclassBMWextendsCar {//此处省略} @DiscriminatorValue("BENZ")注释在子类,就会默认T_CAR表中有DTYPE字段, 查T_CAR表的时候,默认是使用DTYPE='BENZ'条件查询 建表的时候一定要添加DTYPE字段,否则会报:ORA-00904: "T_CAR"."DTYPE": 标识符无效 SELECTDTYPEFROMT_CARWH...
JPA注解@DiscriminatorValue使⽤ ⽗类 @Entity @Table(name = "T_CAR")// 使⽤此注释：T_CAR表中必须添加CAR_TYPE字段,如果不使⽤此注释：表中也必须添加默认的DTYPE字段 @DiscriminatorColumn(name = "CAR_TYPE")public class Car extends EntityBean implements Serializable { // 此处省略...} ⼦类...
@Inheritance注解用来是设置实体类继承关系中的继承策略(inheritance strategy) 1.设置在父类实体类中 2.如果父类没有设置该注解或没有显示设置strategy,默认为SINGLE_TABLE 3.继承策略有三种 实体类可实现继承关系(例如实体类ValuedCustomer继承自实体类Customer),@Inheritance使用在父类,设置继承策略strategy @Inheritance...
Final Update: turns out the @Discriminator thing does not work well with hibernate. I used the @SecondaryTable approach and that took care of this issue for me. Thanks everyone for helping me out! I'm not a hibernate guru but I'm wondering if you need the@DiscriminatorColumnand@Discriminato...
注释的恰当用法是弥补我们在用代码表达意图时遭遇的失败，我用了失败一词，其实是说真的。注释总是一...
Since this is automatically handled by jpa, I have no way of getting this value. We are calling a method that takes an ApplicationProcess as parameter, and I want to avoid using instanceof to check what type it is. Would be cooler if I could do something like applicationProcess.getAp...
Linux 的 I/O 调度器是一个以块式 I/O 访问存储卷的进程，有时也叫磁盘调度器。Linux I/O 调度...
一、结构 You can map an entire class hierarchy to a single table. This table includes columns for all properties of all classes in the hierarchy. The
您可以将鉴别器映射为只读属性：
JPA Annotation DiscriminatorValue Target: TYPE Implemented Interfaces: AnnotationSpecifies the value of the discriminator column for entities of the given type. The DiscriminatorValue annotation can only be specified on a concrete entity class. If the DiscriminatorValue annotation is not specified and ...