不能使用< union-subclass>标识列密钥生成（TABLE_PER_CLASS） [英] Cannot use identity column key generation with <union-subclass> ( TABLE_PER_CLASS )

问题描述

com.something.SuperClass：

  @Entity 
 @Inheritance = InheritanceType.TABLE_PER_CLASS）
 public abstract class SuperClass implements Serializable {
 private static final long serialVersionUID = -695503064509648117L; 
 
 long confirmationCode; 
 
 @Id 
 @GeneratedValue（strategy = GenerationType.AUTO）//导致异常!!! 
 public long getConfirmationCode（）{
 return confirmationCode; 
} 
 
 public void setConfirmationCode（long confirmationCode）{
 this.confirmationCode = confirmationCode; 
} 
} 
  

com.something.SubClass：

  @Entity 
 public abstract class Subclass extends SuperClass {
 private static final long serialVersionUID = 8623159397061057722L ; 
 
字符串名称; 
 
 @Column（nullable = false）
 public String getName（）{
 return name; 
} 
 
 public void setName（String name）{
 this.name = name; 
 
 
 code 
 
 
 
 给我这个例外：  
 
 
 引起：org.hibernate.MappingException：无法使用identity列键
 generation with< union-subclass> ;映射为：com.something.SuperClass 
  
对于我来说，生成ID的最好和最方便的方法是什么？我不想改变我的继承策略。 
   table-per-class继承和 GenerationType.Auto 。 
考虑MsSQL中的标识列。它是基于列的。在每班级表策略中，每个班级使用一个表格，每个表格都有一个ID。 
 
 
 
试试： 
 
 
  @GeneratedValue（strategy = GenerationType.TABLE） 
 
com.something.SuperClass:
@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public abstract class SuperClass implements Serializable {
    private static final long serialVersionUID = -695503064509648117L;

    long confirmationCode;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO) // Causes exception!!!
    public long getConfirmationCode() {
        return confirmationCode;
    }

    public void setConfirmationCode(long confirmationCode) {
        this.confirmationCode = confirmationCode;
    }
}
com.something.SubClass:
@Entity
public abstract class Subclass extends SuperClass {
    private static final long serialVersionUID = 8623159397061057722L;

    String name;

    @Column(nullable = false)
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}
Gives me this exception:
Caused by: org.hibernate.MappingException: Cannot use identity column key
generation with <union-subclass> mapping for: com.something.SuperClass
What's the best and most convenient way for me to generate the ID's? I do not want to change my inheritance strategy.
解决方案
The problem here is that you mix "table-per-class" inheritance and GenerationType.Auto.
Consider an identity column in MsSQL. It is column based. In a "table-per-class" strategy you use one table per class and each one has an ID. 

Try:

@GeneratedValue(strategy = GenerationType.TABLE)

                        
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