java - @OrderColumn 生成更新主键的请求

Question

我使用列表。该列表由一个复合主键组成，该主键也用于对列表进行排序。问题是如果我删除列表中的一个元素(关键化合物)，注解 @OrderColumn 生成更新主键的请求，成本上升异常类型:

[26-05-2011 10:34:18:835] WARN  org.hibernate.util.JDBCExceptionReporter  - SQL Error: 1062, SQLState: 23000  
[26-05-2011 10:34:18:835] ERROR org.hibernate.util.JDBCExceptionReporter  -Duplicate  entry '10-10' for key 'PRIMARY'  
[26-05-2011 10:34:18:835] ERROR org.hibernate.event.def.AbstractFlushingEventListener  - Could not synchronize database state with session org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update  

这是映射的定义:

@ManyToMany(cascade=CascadeType.ALL, fetch = FetchType.LAZY)
@JoinTable(name = "chapter_item", joinColumns = { @JoinColumn(name = "chapter_id", nullable = false, updatable = false) }, inverseJoinColumns = { @JoinColumn(name = "item_id", nullable = false, updatable = false) })
@OrderColumn(name="iorder")
public List<Item> getItems() {
    return items;
}

这是我遇到问题的更新查询:

Hibernate: 
update
    chapter_item 
set
    item_id=? 
where
    chapter_id=? 
    and iorder=?  

我想知道这是否是一个已知的错误，是否有人有解决方案？

Answer 1

关于@OrderColumn，以下文档位于http://docs.oracle.com/javaee/6/api/javax/persistence/OrderColumn.html

Specifies a column that is used to maintain the persistent order of a list. The persistence provider is responsible for maintaining the order upon retrieval and in the database. The persistence provider is responsible for updating the ordering upon flushing to the database to reflect any insertion, deletion, or reordering affecting the list.

所以我们看到持久化提供者，即hibernate负责更新名为iorder的列。 .也有人说:

The OrderColumn annotation is specified on a OneToMany or ManyToMany relationship or on an element collection. The OrderColumn annotation is specified on the side of the relationship that references the collection that is to be ordered. The order column is not visible as part of the state of the entity or embeddable class.

请注意下面的句子:

The order column is not visible as part of the state of the entity or embeddable class.

所以，我建议您考虑不选择 iorder 列吗？对于 @OrderColumn因为它是您的composite key 的一部分并且当您在列表中删除或插入元素时，hibernate 肯定会更新此值 (List<Item>)。

希望，这会有所帮助。