休眠Apache Derby自定义序列 [英] Hibernate Apache Derby Custom Sequence

问题描述

我试图在一个非常简单的映射中使用序列生成器。

我试图在Hibernate的ID序列生成中研究生成器类。

 <？xml version =1.0encoding =UTF-8？> 
<！DOCTYPE hibernate-mapping PUBLIC 
 -  // Hibernate / Hibernate映射DTD 3.0 // EN
http://hibernate.sourceforge.net/hibernate-mapping-3.0 .dtd> 
< hibernate-mapping package =com.test> 
< class name =Customertable =Customer> 
< id name =idcolumn =IDtype =long> 
< generator class =sequence> 
< param name =sequence> CUSTOMER_SEQUENCE< / param> 
< / generator> 
< / id> 
< property name =nametype =stringcolumn =CUSTOMER_NAME/> 
< / class> 
< / hibernate-mapping> 
  

我使用的是Apache Derby，客户表中的ID列只是一个简单的长数据类型。 p>

但是当我尝试执行一个简单的保存时，我遇到了下面的错误。

引起：java.sql .SQLSyntaxErrorException：SEQUENCE'CUSTOMER_SEQUENCE'不存在。
这是否意味着Apache Derby不支持序列生成？谢谢

解决方案

似乎Derby不支持序列生成。从官方德比常见问题解答中引用：

Derby支持生成的标识
列;示例在参考
指南中。 IDENTITY_VAL_LOCAL函数
返回最近分配的
数字。

工作正在为SEQUENCE
支持添加到Derby 10.6。 p>

I am trying to investigate the generator class in the ID sequence generation of Hibernate.

I tried to use the sequence generator on a very simple mapping

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.test">
    <class name="Customer" table="Customer">
        <id name="id" column="ID" type="long">
            <generator class="sequence">
                <param name="sequence">CUSTOMER_SEQUENCE</param>
            </generator>
        </id>
        <property name="name" type="string" column="CUSTOMER_NAME" />
    </class>
</hibernate-mapping>

I am using apache derby, the ID column in the customer table is justa simple long datatype.

But when I try to execute a simple save, I am encountering below error.

Caused by: java.sql.SQLSyntaxErrorException: SEQUENCE 'CUSTOMER_SEQUENCE' does not exist. Does this mean that Apache Derby does not support Sequence Generation? Thanks

解决方案

It seems that Derby doesn't support sequence generation. Quote from official Derby FAQ:

Derby supports generated "identity" columns; examples are in the Reference Guide. The IDENTITY_VAL_LOCAL function returns the most recently assigned number.

Work is underway to add SEQUENCE support to Derby 10.6.

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