Question

我已经将我的课程映射为以下（省略其他字段仅作为ID事项）：

@Entity
@Table(name = "MODEL_GROUP")
@Cache(usage = CacheConcurrencyStrategy.TRANSACTIONAL)
public class SettlementModelGroup implements Serializable
{


@Id
@GeneratedValue(generator = "MODEL_GROUP_SEQ", strategy = GenerationType.SEQUENCE)
@GenericGenerator(name = "MODEL_GROUP_SEQ",
        strategy = "sequence",
        parameters = @Parameter(name = "sequence", value = "SEQ_MODEL_GROUP_MODEL_GROUP_ID"))
@Column(name = "MODEL_GROUP_ID", nullable = false)
private Integer modelId;
}

当我保存新对象时：

Integer modelGroupId = sessionFactory.getCurrentSession().save( modelGroup );
System.out.println( modelGroupId );

ID设置为例如23，但是当我查看数据库时，它实际上是24。这导致了许多问题，因为我稍后使用此ID。不知道为什么会出现这个差距？

SQL日志显示一切正常（我这么认为）：

Hibernate: 
 select
     SEQ_MODEL_GROUP_MODEL_GROUP_ID.nextval 
 from
     dual
Hibernate: 
 insert 
 into
     MODEL_GROUP
     (DOMAIN_ID, DESCRIPTION, NAME, PERIOD_TYPE_ID, MODEL_GROUP_TYPE_ID, STATUS_ID, OWNER_ID, MODEL_GROUP_ID) 
 values
     (?, ?, ?, ?, ?, ?, ?, ?)

触发和序列：

CREATE SEQUENCE "SEQ_MODEL_GROUP_MODEL_GROUP_ID" 
  INCREMENT BY 1 
  START WITH 1 
  NOMAXVALUE 
  MINVALUE 1 
 NOCYCLE 
 NOCACHE 
 NOORDER
;

CREATE OR REPLACE TRIGGER "TRG_MODEL_GROUP_MODEL_GROUP_ID" 
BEFORE INSERT 
ON "MODEL_GROUP" 
FOR EACH ROW 
WHEN (NEW."MODEL_GROUP_ID" is NULL)
BEGIN 
    SELECT "SEQ_MODEL_GROUP_MODEL_GROUP_ID".NEXTVAL 
    INTO :NEW."MODEL_GROUP_ID" 
    FROM DUAL; 
END;

Answer 1

显然，当Hibernate向您的数据库询问ID的nextValue时，它也会触发Trigger。因此，当我要求ID时，我得到了数字23但是当通过提交事务实际保存到数据库时，它再次增加，所以我得到了24。解决方案如下所述：

HIbernate issue with Oracle Trigger for generating id from a sequence

为了使其正常工作，我更改了Trigger：

CREATE OR REPLACE TRIGGER "TRG_MODEL_GROUP_MODEL_GROUP_ID" 
BEFORE INSERT 
ON "MODEL_GROUP" 
FOR EACH ROW 
WHEN (NEW."MODEL_GROUP_ID" is NULL)
BEGIN 
    SELECT "SEQ_MODEL_GROUP_MODEL_GROUP_ID".NEXTVAL 
    INTO :NEW."MODEL_GROUP_ID" 
    FROM DUAL; 
END;

hibernate和oracle序列GenericGenerator创建差距

1 个答案: