hibernate id generator
来源:互联网 发布:网络交易监督管理办法 编辑:程序博客网 时间:2024/05/04 13:50
Generator
The optional <generator>
child element names a Java class used to generate unique identifiers for instances of the persistent class. If any parameters are required to configure or initialize the generator instance, they are passed using the <param>
element.
<id name="id" type="long" column="cat_id"> <generator class="org.hibernate.id.TableHiLoGenerator"> <param name="table">uid_table</param> <param name="column">next_hi_value_column</param> </generator></id>
All generators implement the interface org.hibernate.id.IdentifierGenerator
. This is a very simple interface. Some applications can choose to provide their own specialized implementations, however, Hibernate provides a range of built-in implementations. The shortcut names for the built-in generators are as follows:
increment
generates identifiers of type
long
,short
orint
that are unique only when no other process is inserting data into the same table. Do not use in a cluster.identity
supports identity columns in DB2, MySQL, MS SQL Server, Sybase and HypersonicSQL. The returned identifier is of type
long
,short
orint
.sequence
uses a sequence in DB2, PostgreSQL, Oracle, SAP DB, McKoi or a generator in Interbase. The returned identifier is of type
long
,short
orint
hilo
uses a hi/lo algorithm to efficiently generate identifiers of type
long
,short
orint
, given a table and column (by defaulthibernate_unique_key
andnext_hi
respectively) as a source of hi values. The hi/lo algorithm generates identifiers that are unique only for a particular database.seqhilo
uses a hi/lo algorithm to efficiently generate identifiers of type
long
,short
orint
, given a named database sequence.uuid
uses a 128-bit UUID algorithm to generate identifiers of type string that are unique within a network (the IP address is used). The UUID is encoded as a string of 32 hexadecimal digits in length.
guid
uses a database-generated GUID string on MS SQL Server and MySQL.
native
selects
identity
,sequence
orhilo
depending upon the capabilities of the underlying database.assigned
lets the application assign an identifier to the object before
save()
is called. This is the default strategy if no<generator>
element is specified.select
retrieves a primary key, assigned by a database trigger, by selecting the row by some unique key and retrieving the primary key value.
foreign
uses the identifier of another associated object. It is usually used in conjunction with a
<one-to-one>
primary key association.sequence-identity
a specialized sequence generation strategy that utilizes a database sequence for the actual value generation, but combines this with JDBC3 getGeneratedKeys to return the generated identifier value as part of the insert statement execution. This strategy is only supported on Oracle 10g drivers targeted for JDK 1.4. Comments on these insert statements are disabled due to a bug in the Oracle drivers.
- hibernate id Generator
- hibernate id Generator
- hibernate id Generator
- Hibernate Id Generator
- hibernate id Generator
- hibernate id generator
- hibernate id Generator
- hibernate 主键 id Generator
- hibernate id Generator详解
- Hibernate id的generator
- Hibernate Id Generator的解释
- Hibernate Id Generator的解释
- Hibernate Id Generator的解释
- Hibernate Id Generator的解释 .
- hibernate id Generator的类型
- hibernate id Generator
- hibernate id 及id Generator的详解
- hibernate generator class="" id详解
- 分享一个安卓系统的php环境,http+php+mysql,
- 摄影师拍蜗牛乘树叶花下避雨 似撑小伞泛舟
- 数据库学习(sql)----一些理论
- ActionContext和ServletActionContext小结
- 声卡 虚仪示波器 频谱仪 扫频仪 基于labview 更新版
- hibernate id generator
- PhpStorm 注册码
- 2013年02月18日 工作总结
- PHP实现文件上传的例子(附详细源码)
- kmalloc、vmalloc、malloc的区别
- RubyMotion 初玩
- 使用ICallbackEventHandler接口更高效实现Ajax
- 使用网上流传的一个数据库连接池在Proxy.newProxyInstance处引起 java.lang.ClassCastException 问题的解决方法
- 在哪里创业与怎么创业