describe:
i have four entity:person,autor,publication,work
person<-->author one2one
author<-->publication one2many
autthor<-->work many2many
version of Hibernate:2.1.1
error:
net.sf.hibernate.id.IdentifierGenerationException: ids for this class must be manually assigned before calling save(): com.many2many.Work

at net.sf.hibernate.id.Assigned.generate(Assigned.java:26)

at net.sf.hibernate.impl.SessionImpl.saveWithGeneratedIdentifier(SessionImpl.java:727)

at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:717)

at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1322)

at net.sf.hibernate.engine.Cascades$4.cascade(Cascades.java:114)

at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:436)

at net.sf.hibernate.engine.Cascades.cascadeCollection(Cascades.java:526)

at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:452)

at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:503)

at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:892)

at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:817)

at net.sf.hibernate.impl.SessionImpl.saveWithGeneratedIdentifier(SessionImpl.java:740)

at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:717)

at com.many2many.hibernateclienttest.main(hibernateclienttest.java:162)

source code:
person.java

package com.many2many;

/**
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2003</p>
* <p>Company: </p>
* @author not attributable
* @version 1.0
*/

public class Person {
public Person() {
}

private String PersonID;
public void setPersonID(java.lang.String PersonID)
{
this.PersonID = PersonID;
}

public java.lang.String getPersonID()
{
return this.PersonID;
}

private java.lang.String NAME = null;
public void setNAME(java.lang.String NAME)
{
this.NAME = NAME;
}
public java.lang.String getNAME()
{
return this.NAME;
}

private java.lang.String EMAIL = null;
public void setEMAIL(java.lang.String EMAIL)
{
this.EMAIL = EMAIL;
}
public java.lang.String getEMAIL()
{
return this.EMAIL;
}

}

person.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping SYSTEM "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="com.many2many.Person" table="DB_PERSON">
<id name="PersonID" type="java.lang.String" unsaved-value="any">
<column name="DB_PERSONID" sql-type="VARCHAR(911)" not-null="true"
length="41"/>
<generator class="assigned"/>
</id>

<property name="NAME" type="java.lang.String" update="true" insert="true">
<column name="DB_NAME" sql-type="VARCHAR(922)" length="400"
not-null="true"/>
</property>

<property name="EMAIL" type="java.lang.String" update="true" insert="true">
<column name="DB_EMAIL" sql-type="VARCHAR(933)" length="512"
not-null="true"/>
</property>
</class>
</hibernate-mapping>

author.java

package com.many2many;

/**
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2003</p>
* <p>Company: </p>
* @author not attributable
* @version 1.0
*/

public class Author {
public Author() {
}

private java.lang.String AUTHORID;
public void setAUTHORID(java.lang.String AUTHORID)
{
this.AUTHORID = AUTHORID;
}
public java.lang.String getAUTHORID()
{
return this.AUTHORID;
}

private java.lang.String ALIAS = null;
public void setALIAS(java.lang.String ALIAS)
{
this.ALIAS = ALIAS;
}
public java.lang.String getALIAS()
{
return this.ALIAS;
}

private com.many2many.Person objPerson = null;
public void setobjPerson(com.many2many.Person objPerson)
{
this.objPerson = objPerson;
}
public com.many2many.Person getobjPerson()
{
return this.objPerson;
}

private java.util.Set publications = new java.util.HashSet();
public void setpublications(java.util.Set publications)
{
this.publications = publications;
}
public java.util.Set getpublications()
{
return this.publications;
}

public void addpublications(com.many2many.Publication objPublication)
{
this.publications.add(objPublication);
}

private java.util.Set works = new java.util.HashSet();
public void setworks(java.util.Set works)
{
this.works = works;
}
public java.util.Set getworks()
{
return this.works;
}
}

author.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping SYSTEM "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="com.many2many.Author" table="DB_AUTHOR">
<id name="AUTHORID" type="java.lang.String" unsaved-value="any">
<column name="DB_AUTHORID" sql-type="VARCHAR2(911)" not-null="true"/>
<generator class="foreign">
<param name="property">objPerson</param>
</generator>
</id>

<property name="ALIAS" type="java.lang.String" update="true" insert="true">
<column name="DB_ALIAS" sql-type="VARCHAR2(922)" length="400"
not-null="false"/>
</property>

<one-to-one name="objPerson" class="com.many2many.Person" cascade="all" constrained="true"
outer-join="auto" access="property"/>

<set table="DB_PUBLICATION" name="publications" lazy="true" inverse="true" cascade="all" sort="unsorted">
<key column="DB_AUTHORID"/>
<one-to-many class="com.many2many.Publication"/>
</set>

<set table="DB_WORK" name="works" lazy="true" inverse="true" cascade="all" sort="unsorted">
<key column="DB_AUTHORID"/>
<many-to-many class="com.many2many.Work" column="DB_WORKID" outer-join="auto"/>
</set>
</class>
</hibernate-mapping>

publication.java

package com.many2many;

/**
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2003</p>
* <p>Company: </p>
* @author not attributable
* @version 1.0
*/

public class Publication {
public Publication() {
}

private String id = null;
public void setid(java.lang.String id)
{
this.id = id;
}
public java.lang.String getid()
{
return this.id;
}

private String bookName = null;
public void setbookName(java.lang.String bookName)
{
this.bookName = bookName;
}
public java.lang.String getbookName()
{
return this.bookName;
}

private String dateTime = null;
public void setdateTime(java.lang.String dateTime)
{
this.dateTime = dateTime;
}
public java.lang.String getdateTime()
{
return this.dateTime;
}

private String authorId = null;
public void setauthorId(java.lang.String authorId)
{
this.authorId = authorId;
}
public java.lang.String getauthorId()
{
return this.authorId;
}

private com.many2many.Author objAuthor = null;
public void setobjAuthor(com.many2many.Author objAuthor)
{
this.objAuthor = objAuthor;
}
public com.many2many.Author getobjAuthor()
{
return this.objAuthor;
}
}

publication.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping SYSTEM "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="com.many2many.Publication" table="DB_PUBLICATION">
<id name="id" type="java.lang.String" unsaved-value="any">
<column name="DB_PUBLICATIONID" sql-type="VARCHAR2(911)" not-null="true"
length="40"/>
<generator class="assigned"/>
</id>

<property name="bookName" type="java.lang.String" update="true" insert="true">
<column name="DB_BOOKNAME" sql-type="VARCHAR2(922)" length="400"
not-null="false"/>
</property>

<property name="dateTime" type="java.lang.String" update="true" insert="true">
<column name="DB_DATETIME" sql-type="VARCHAR2(933)" length="400"
not-null="false"/>
</property>

<many-to-one name="objAuthor" class="com.many2many.Publication" cascade="all"
column="DB_AUTHORID" not-null="false" update="true" insert="false"
outer-join="auto"/>

</class>
</hibernate-mapping>

work.java

package com.many2many;

/**
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2003</p>
* <p>Company: </p>
* @author not attributable
* @version 1.0
*/

public class Work {
public Work() {
}

//
private String WorkID = null;
public void setWorkID(java.lang.String WorkID)
{
this.WorkID = WorkID;
}
public java.lang.String getWorkID()
{
return this.WorkID;
}
//
private String title = null;
public void settitle(java.lang.String title)
{
this.title = title;
}
public java.lang.String gettitle()
{
return this.title;
}
//
private java.util.Set authors = new java.util.HashSet();
public void setauthors(java.util.Set objauthors)
{
this.authors = objauthors;
}
public java.util.Set getauthors()
{
return this.authors;
}

}

work.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping SYSTEM "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="com.many2many.Work" table="DB_WORK">
<id name="WorkID" type="java.lang.String" unsaved-value="any">
<column name="DB_WORKID" sql-type="VARCHAR2(911)" not-null="true"
length="40"/>
<generator class="assigned"/>
</id>

<property name="title" type="java.lang.String" update="true" insert="true">
<column name="DB_TITLE" sql-type="VARCHAR2(933)" length="400"
not-null="false"/>
</property>

<set table="DB_AUTHOR" name="authors" lazy="true" inverse="true" cascade="all" sort="unsorted">
<key column="DB_WORKID"/>
<many-to-many class="com.many2many.Author" column="DB_AUTHORID" outer-join="auto"/>
</set>
</class>
</hibernate-mapping>


the code of client is :

package com.many2many;

import net.sf.hibernate.Session;
import net.sf.hibernate.SessionFactory;
import net.sf.hibernate.Transaction;
import net.sf.hibernate.cfg.Configuration;
import net.sf.hibernate.tool.hbm2ddl.SchemaExport;
import net.sf.hibernate.MappingException;
import net.sf.hibernate.HibernateException;

/**
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2003</p>
* <p>Company: </p>
* @author not attributable
* @version 1.0
*/

public class hibernateclienttest {
public hibernateclienttest() {
}

private static net.sf.hibernate.Transaction tx;
private static net.sf.hibernate.Session objSession;
public static void main(String [] agrs) throws Exception
{
try
{
Configuration objConfig = new Configuration();
SessionFactory objSessionFactory = objConfig.configure().
buildSessionFactory();

SchemaExport objSchema = new SchemaExport(objConfig);
objSchema.setOutputFile("SaveThePeople.SQL");
objSchema.create(true, true);

//
net.sf.hibernate.Session objSession = objSessionFactory.openSession();
tx = objSession.beginTransaction();

com.many2many.Person objPerson1 = new com.many2many.Person();
objPerson1.setPersonID("Person1");
objPerson1.setNAME("1name");
objPerson1.setEMAIL("1@163.com");
com.many2many.Person objPerson2 = new com.many2many.Person();
objPerson2.setPersonID("Person2");
objPerson2.setNAME("2name");
objPerson2.setEMAIL("2@163.com");
com.many2many.Person objPerson3 = new com.many2many.Person();
objPerson3.setPersonID("Person3");
objPerson3.setNAME("3name");
objPerson3.setEMAIL("3@163.com");
com.many2many.Person objPerson4 = new com.many2many.Person();
objPerson4.setPersonID("Person4");
objPerson4.setNAME("4name");
objPerson4.setEMAIL("4@163.com");

//objSession.save(objPerson1);
//objSession.save(objPerson2);
//objSession.save(objPerson3);

com.many2many.Publication objPublication1 = new com.many2many.Publication();
objPublication1.setid("publication1");
objPublication1.setbookName("english book");
objPublication1.setdateTime("20031010");
com.many2many.Publication objPublication2 = new com.many2many.Publication();
objPublication2.setid("publication2");
objPublication2.setbookName("japan");
objPublication2.setdateTime("19991011");
com.many2many.Publication objPublication3 = new com.many2many.Publication();
objPublication3.setid("publication3");
objPublication3.setbookName("program");
objPublication3.setdateTime("20040107");

com.many2many.Author objAuthor1 = new com.many2many.Author();
objAuthor1.setALIAS("1alias//★
objAuthor1.setobjPerson(objPerson1); //●

objAuthor1.addpublications(objPublication1); objAuthor1.addpublications(objPublication2); objAuthor1.addpublications(objPublication3);
objPublication1.setobjAuthor(objAuthor1);
objPublication2.setobjAuthor(objAuthor1);
objPublication3.setobjAuthor(objAuthor1);

com.many2many.Author objAuthor2 = new com.many2many.Author();
objAuthor2.setALIAS("2alias");
objAuthor2.setobjPerson(objPerson2);

com.many2many.Author objAuthor3 = new com.many2many.Author();
objAuthor3.setALIAS("2alias");
objAuthor3.setobjPerson(objPerson3);

com.many2many.Work objWork1 = new com.many2many.Work();
objWork1.setWorkID("work1");
objWork1.settitle("1title");
com.many2many.Work objWork2 = new com.many2many.Work();
objWork1.setWorkID("work2");
objWork2.settitle("2title");
com.many2many.Work objWork3 = new com.many2many.Work();
objWork1.setWorkID("work3");
objWork3.settitle("3title");
com.many2many.Work objWork4 = new com.many2many.Work();
objWork1.setWorkID("work4");
objWork4.settitle("4title");

objWork1.getauthors().add(objAuthor1);

objWork2.getauthors().add(objAuthor1);
objWork2.getauthors().add(objAuthor2);

objWork3.getauthors().add(objAuthor1);
objWork3.getauthors().add(objAuthor2);
objWork3.getauthors().add(objAuthor3);

objWork4.getauthors().add(objAuthor1);
objWork4.getauthors().add(objAuthor2);
objWork4.getauthors().add(objAuthor3);

objAuthor1.getworks().add(objWork1);
objAuthor1.getworks().add(objWork2);
objAuthor1.getworks().add(objWork3);
objAuthor1.getworks().add(objWork4);

objAuthor2.getworks().add(objWork2);
objAuthor2.getworks().add(objWork3);
objAuthor2.getworks().add(objWork4);

objAuthor3.getworks().add(objWork3);
objAuthor3.getworks().add(objWork4);

objSession.save(objAuthor1);
objSession.save(objAuthor2);
objSession.save(objAuthor3);

objSession.save(objWork1);
objSession.save(objWork2);
objSession.save(objWork3);
objSession.save(objWork4);

tx.commit();
return;
}
catch(MappingException me)
{
me.printStackTrace();
if(objSession!=null)
{
tx.rollback();
}
}
catch(HibernateException he)
{
he.printStackTrace();
if(objSession!=null)
{
tx.rollback();
}
}
finally
{
objSession.close();
}
}

}

the whole error code in the jbuilder9:
E:\JBuilder9\jdk1.4\bin\javaw -classpath "F:\ElsaJava\CodeHibernate\hibernate\classes;F:\ElsaJava\database\hibernate2.1.1\lib\ant.jar;F:\ElsaJava\database\hibernate2.1.1\lib\c3p0.jar;F:\ElsaJava\database\hibernate2.1.1\lib\cglib2.jar;F:\ElsaJava\database\hibernate2.1.1\lib\commons-collections.jar;F:\ElsaJava\database\hibernate2.1.1\lib\commons-dbcp.jar;F:\ElsaJava\database\hibernate2.1.1\lib\commons-lang.jar;F:\ElsaJava\database\hibernate2.1.1\lib\commons-logging.jar;F:\ElsaJava\database\hibernate2.1.1\lib\commons-pool.jar;F:\ElsaJava\database\hibernate2.1.1\lib\concurrent.jar;F:\ElsaJava\database\hibernate2.1.1\lib\connector.jar;F:\ElsaJava\database\hibernate2.1.1\lib\dom4j.jar;F:\ElsaJava\database\hibernate2.1.1\lib\ehcache.jar;F:\ElsaJava\database\hibernate2.1.1\lib\jaas.jar;F:\ElsaJava\database\hibernate2.1.1\lib\jboss-cache.jar;F:\ElsaJava\database\hibernate2.1.1\lib\jboss-common.jar;F:\ElsaJava\database\hibernate2.1.1\lib\jboss-jmx.jar;F:\ElsaJava\database\hibernate2.1.1\lib\jboss-system.jar;F:\ElsaJava\database\hibernate2.1.1\lib\jcs.jar;F:\ElsaJava\database\hibernate2.1.1\lib\jdbc2_0-stdext.jar;F:\ElsaJava\database\hibernate2.1.1\lib\jgroups.jar;F:\ElsaJava\database\hibernate2.1.1\lib\jta.jar;F:\ElsaJava\database\hibernate2.1.1\lib\junit.jar;F:\ElsaJava\database\hibernate2.1.1\lib\log4j.jar;F:\ElsaJava\database\hibernate2.1.1\lib\odmg.jar;F:\ElsaJava\database\hibernate2.1.1\lib\optional.jar;F:\ElsaJava\database\hibernate2.1.1\lib\oscache.jar;F:\ElsaJava\database\hibernate2.1.1\lib\proxool.jar;F:\ElsaJava\database\hibernate2.1.1\lib\swarmcache.jar;F:\ElsaJava\database\hibernate2.1.1\lib\xalan.jar;F:\ElsaJava\database\hibernate2.1.1\lib\xerces.jar;F:\ElsaJava\database\hibernate2.1.1\lib\xml-apis.jar;F:\ElsaJava\database\hibernate2.1.1\hibernate2.jar;E:\oracle\ora81\jdbc\lib\classes12.jar;E:\JBuilder9\thirdparty\junit3.8\junit.jar;E:\JBuilder9\lib\unittest.jar;E:\JBuilder9\jdk1.4\lib\dt.jar;E:\JBuilder9\jdk1.4\lib\htmlconverter.jar;E:\JBuilder9\jdk1.4\lib\tools.jar;E:\JBuilder9\jdk1.4\jre\lib\charsets.jar;E:\JBuilder9\jdk1.4\jre\lib\jaws.jar;E:\JBuilder9\jdk1.4\jre\lib\jce.jar;E:\JBuilder9\jdk1.4\jre\lib\jsse.jar;E:\JBuilder9\jdk1.4\jre\lib\rt.jar;E:\JBuilder9\jdk1.4\jre\lib\sunrsasign.jar;E:\JBuilder9\jdk1.4\jre\lib\im\indicim.jar;E:\JBuilder9\jdk1.4\jre\lib\ext\dnsns.jar;E:\JBuilder9\jdk1.4\jre\lib\ext\ldapsec.jar;E:\JBuilder9\jdk1.4\jre\lib\ext\localedata.jar;E:\JBuilder9\jdk1.4\jre\lib\ext\sunjce_provider.jar;E:\JBuilder9\jdk1.4\demo\plugin\jfc\Java2D\Java2Demo.jar;E:\JBuilder9\jdk1.4\demo\jfc\Java2D\Java2Demo.jar" -Xdebug -Xnoagent -Djava.compiler=NONE -Xrunjdwp:transport=dt_socket,address=survival:1861,suspend=y com.many2many.hibernateclienttest
08:22:16,381 INFO Environment:432 - Hibernate 2.1.1

08:22:16,421 INFO Environment:466 - loaded properties from resource hibernate.properties: {hibernate.cglib.use_reflection_optimizer=true}

08:22:16,441 INFO Environment:481 - using CGLIB reflection optimizer

08:22:18,284 INFO Configuration:843 - configuring from resource: /hibernate.cfg.xml

08:22:18,284 INFO Configuration:815 - Configuration resource: /hibernate.cfg.xml

08:22:20,637 INFO Configuration:300 - Mapping resource: ./com/many2many/Person.hbm.xml

08:22:21,228 INFO Binder:225 - Mapping class: com.many2many.Person -> DB_PERSON

08:22:21,759 INFO Configuration:300 - Mapping resource: ./com/many2many/Author.hbm.xml

08:22:21,949 INFO Binder:225 - Mapping class: com.many2many.Author -> DB_AUTHOR

08:22:22,109 INFO Binder:534 - Mapping collection: com.many2many.Author.works -> DB_WORK

08:22:22,119 INFO Configuration:300 - Mapping resource: ./com/many2many/Publication.hbm.xml

08:22:22,300 INFO Binder:225 - Mapping class: com.many2many.Publication -> DB_PUBLICATION

08:22:22,310 INFO Configuration:300 - Mapping resource: ./com/many2many/Work.hbm.xml

08:22:22,510 INFO Binder:225 - Mapping class: com.many2many.Work -> DB_WORK

08:22:22,510 INFO Binder:534 - Mapping collection: com.many2many.Work.authors -> DB_AUTHOR

08:22:22,520 INFO Configuration:998 - Configured SessionFactory: null

08:22:22,520 INFO Configuration:584 - processing one-to-many association mappings

08:22:22,530 INFO Binder:1139 - Mapping collection: com.many2many.Author.publications -> DB_PUBLICATION

08:22:22,580 INFO Configuration:593 - processing one-to-one association property references

08:22:22,620 INFO Configuration:618 - processing foreign key constraints

08:22:22,840 INFO Dialect:82 - Using dialect: net.sf.hibernate.dialect.OracleDialect

08:22:22,850 INFO SettingsFactory:62 - Use outer join fetching: true

08:22:22,880 INFO DriverManagerConnectionProvider:41 - Using Hibernate built-in connection pool (not for production use!)

08:22:22,880 INFO DriverManagerConnectionProvider:42 - Hibernate connection pool size: 20

08:22:22,900 INFO DriverManagerConnectionProvider:71 - using driver: oracle.jdbc.driver.OracleDriver at URL: jdbc:oracle:oci8:@platform

08:22:22,910 INFO DriverManagerConnectionProvider:72 - connection properties: {user=hibernate, password=hibernate}

08:22:22,950 INFO TransactionManagerLookupFactory:33 - No TransactionManagerLookup configured (in JTA environment, use of process level read-write cache is not recommended)

08:22:26,395 INFO SettingsFactory:89 - Use scrollable result sets: true

08:22:26,395 INFO SettingsFactory:90 - JDBC 2 max batch size: 15

08:22:26,405 INFO SettingsFactory:96 - echoing all SQL to stdout

08:22:26,405 INFO SettingsFactory:99 - Query language substitutions: {}

08:22:26,405 INFO SettingsFactory:110 - cache provider: net.sf.ehcache.hibernate.Provider

08:22:26,435 INFO Configuration:1057 - instantiating and configuring caches

08:22:27,096 INFO SessionFactoryImpl:119 - building session factory

08:22:29,069 INFO SessionFactoryObjectFactory:82 - no JNDI name configured

08:22:29,079 INFO Dialect:82 - Using dialect: net.sf.hibernate.dialect.OracleDialect

08:22:29,089 INFO Configuration:584 - processing one-to-many association mappings

08:22:29,089 INFO Configuration:593 - processing one-to-one association property references

08:22:29,089 INFO Configuration:618 - processing foreign key constraints

08:22:29,109 INFO Configuration:584 - processing one-to-many association mappings

08:22:29,109 INFO Configuration:593 - processing one-to-one association property references

08:22:29,109 INFO Configuration:618 - processing foreign key constraints

08:22:29,119 INFO SchemaExport:98 - Running hbm2ddl schema export

08:22:29,129 INFO SchemaExport:112 - writing generated schema to file: SaveThePeople.SQL

08:22:29,179 INFO SchemaExport:117 - exporting generated schema to database

08:22:29,189 INFO DriverManagerConnectionProvider:41 - Using Hibernate built-in connection pool (not for production use!)

08:22:29,189 INFO DriverManagerConnectionProvider:42 - Hibernate connection pool size: 20

08:22:29,189 INFO DriverManagerConnectionProvider:71 - using driver: oracle.jdbc.driver.OracleDriver at URL: jdbc:oracle:oci8:@platform

08:22:29,240 INFO DriverManagerConnectionProvider:72 - connection properties: {user=hibernate, password=hibernate}

alter table DB_AUTHOR drop constraint FK3F6B206C1124BE87

alter table DB_PUBLICATION drop constraint FK97ACCFCB1124BE87

drop table DB_AUTHOR cascade constraints

drop table DB_PUBLICATION cascade constraints

drop table DB_WORK cascade constraints

drop table DB_PERSON cascade constraints

create table DB_AUTHOR (
DB_AUTHORID VARCHAR2(911) not null,
DB_ALIAS VARCHAR2(922),
DB_WORKID VARCHAR2(255) not null,
primary key (DB_WORKID, DB_AUTHORID)
)

create table DB_PUBLICATION (
DB_PUBLICATIONID VARCHAR2(911) not null,
DB_BOOKNAME VARCHAR2(922),
DB_DATETIME VARCHAR2(933),
DB_AUTHORID VARCHAR2(40),
primary key (DB_PUBLICATIONID)
)

create table DB_WORK (
DB_WORKID VARCHAR2(911) not null,
DB_TITLE VARCHAR2(933),
DB_AUTHORID VARCHAR2(255) not null,
primary key (DB_AUTHORID, DB_WORKID)
)

create table DB_PERSON (
DB_PERSONID VARCHAR(911) not null,
DB_NAME VARCHAR(922) not null,
DB_EMAIL VARCHAR(933) not null,
primary key (DB_PERSONID)
)

alter table DB_AUTHOR add constraint FK3F6B206C1124BE87 foreign key (DB_AUTHORID) references DB_PERSON

alter table DB_PUBLICATION add constraint FK97ACCFCB1124BE87 foreign key (DB_AUTHORID) references DB_PUBLICATION

08:22:30,632 INFO SchemaExport:160 - schema export complete

08:22:30,642 INFO DriverManagerConnectionProvider:137 - cleaning up connection pool: jdbc:oracle:oci8:@platform

08:22:30,772 INFO DriverManagerConnectionProvider:137 - cleaning up connection pool: jdbc:oracle:oci8:@platform

net.sf.hibernate.id.IdentifierGenerationException: ids for this class must be manually assigned before calling save(): com.many2many.Work

at net.sf.hibernate.id.Assigned.generate(Assigned.java:26)

at net.sf.hibernate.impl.SessionImpl.saveWithGeneratedIdentifier(SessionImpl.java:727)

at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:717)

at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1322)

at net.sf.hibernate.engine.Cascades$4.cascade(Cascades.java:114)

at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:436)

at net.sf.hibernate.engine.Cascades.cascadeCollection(Cascades.java:526)

at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:452)

at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:503)

at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:892)

at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:817)

at net.sf.hibernate.impl.SessionImpl.saveWithGeneratedIdentifier(SessionImpl.java:740)

at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:717)

at com.many2many.hibernateclienttest.main(hibernateclienttest.java:162)

read about the generator types, and use the appropriate type for your db circumstances. Hibernate is seeing your id field not set, but the map is set to "assigned"

James

in the code of java:
objWork1.setWorkID("....");
objWork1.settitle("....");
com.many2many.Work objWork2 = new com.many2many.Work();
objWork1.setWorkID("....");
objWork2.settitle("...");
com.many2many.Work objWork3 = new com.many2many.Work();
objWork1.setWorkID("...");
objWork3.settitle("...");
com.many2many.Work objWork4 = new com.many2many.Work();
objWork1.setWorkID("...");
objWork4.settitle("...");

.... stand for some value!

in the xml of hbm
<id name="WorkID" type="java.lang.String" unsaved-value="any">
<column name="DB_WORKID" sql-type="VARCHAR2(911)" not-null="true"
length="40"/>
<generator class="assigned"/>
</id>

it looks ok,but got the error code!

Looks like you are setting the id, before calling save, so I wonder if it is the unsaved-value="any". I've always used sequences when using oracle, accept when using composite ids, so I haven't seen this problem.
unsaved-value="null" seems more appropriate, then adding a timestamp, or version thing to your objects.

James

One more thing that may help. Did you see the author-work example at the end of the manual in the examples section?

I may not understand your model well, here's some questions:

If the relationship between author/work is M:M, there should be 3 tables, 1 for author, 1 for work, and 1 for the "intersection" table. Based on the schema you show, I don't see that, but possibly i'm confused by the difference with work, and a publication.

--James