I have created a small program in hibernate.I am actually using p[ostgres database.

While running the program i get the following exceptiom :
Exception in thread "main" org.hibernate.exception.SQLGrammarException: could not get next sequence value
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:67)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.id.SequenceGenerator.generate(SequenceGenerator.java:96)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:99)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:187)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:172)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:535)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:523)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:519)
at com.hibernate.util.ApplicationManager.WriteData(ApplicationManager.java:41)
at com.hibernate.util.ApplicationManager.main(ApplicationManager.java:21)
Caused by: org.postgresql.util.PSQLException: ERROR: syntax error at or near "value"
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:1548)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1316)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:191)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:452)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:351)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:255)
at org.hibernate.id.SequenceGenerator.generate(SequenceGenerator.java:75)
... 11 more


I have created a sequence and also included it in the hibernate configuration file.

Hi ,
I too use the sequence for id generation but in oracle.
Can you post your mapping file so that it is more clear

This is the way i use it in my mapping file.
I hope this helps:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="domainobject">

<class name="RecommendedAction" table="RECOMMENDED_ACTIONS">
<id name="id" column="id" type="integer">
<generator class="native">
<param name="sequence">recommended_actions_seq</param>
</generator>
</id>
<property name="name" type="string" column="name"/>
<property name="description" type="string" column="description"/>
<many-to-one name="automatedScript" column="script_id" outer-join = "true" class="AutomatedScript" />
</class>

<query name="RecommendedAction.getAllRecommendedActions">
from RecommendedAction
</query>
</hibernate-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>
<class name="com.hibernate.beans.Event" table="Event">
<id name="id" column="event_id">
<generator class="sequence">
<param name="sequence">event_seq</param>
</generator>
</id>
<property name="date" type="timestamp" column="date_val"/>
<property name="title"/>

</class>
</hibernate-mapping>


This is my mapping file.But if i use "native" instead of sequence then i get the following exception :

Exception in thread "main" org.hibernate.exception.ConstraintViolationException: could not insert: [com.hibernate.beans.Event]
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:71)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.id.insert.AbstractSelectingDelegate.performInsert(AbstractSelectingDelegate.java:40)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2158)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2638)
at org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:48)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:248)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:298)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:181)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:107)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:187)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:172)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:535)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:523)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:519)
at com.hibernate.util.ApplicationManager.WriteData(ApplicationManager.java:41)
at com.hibernate.util.ApplicationManager.main(ApplicationManager.java:21)
Caused by: org.postgresql.util.PSQLException: ERROR: null value in column "event_id" violates not-null constraint
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:1548)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1316)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:191)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:452)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:351)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:305)
at org.hibernate.id.insert.AbstractSelectingDelegate.performInsert(AbstractSelectingDelegate.java:33)
... 17 more

Hi actually in my hibernate.cfg.xml i changed the dialect property from org.hibernate.dialect.HSQLDialect to org.hibernate.dialect.PostgreSQLDialec

When i run the program now, i get the following error


Exception in thread "main" org.hibernate.HibernateException: identifier of an instance of com.hibernate.beans.Event was altered from 1 to 0
at org.hibernate.event.def.DefaultFlushEntityEventListener.checkId(DefaultFlushEntityEventListener.java:58)
at org.hibernate.event.def.DefaultFlushEntityEventListener.getValues(DefaultFlushEntityEventListener.java:157)
at org.hibernate.event.def.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:113)
at org.hibernate.event.def.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:196)
at org.hibernate.event.def.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:76)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:26)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:338)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
at com.hibernate.util.ApplicationManager.WriteData(ApplicationManager.java:46)
at com.hibernate.util.ApplicationManager.main(ApplicationManager.java:21)


Can anyone put comments on this.

Hi ksriram,

what is the code that caused the exception? And if you want more feedback, use the code tag when sending code or config stuff. Or it's hard to read. e.g:


chucky

I actually resolved the problem.

1) I changed my the dialect from org.hibernate.dialect.HSQLDialect to org.hibernate.dialect.PostgreSQLDialect.

This was one of the mistakes.I learn t that we should always use the underlying database's dialect.

2) The problem was in my POJO class.I had declared a files as int rather than Integer.

In Hibernate, the POJO classes filed/variables should have only wrapper class.
But in a normal bean file we can have primitive data type.

I want to know the reason why a Wrapper class is used instead of primitive data type in the POJO classes.

Hi ksriram,

wrapper classes are preferred because fields can be nullable. You achieve that with primitives.

Sorry,
you CAN'T achieve that with primitives.

Hi, you might find this thread usefull: http://forum.hibernate.org/viewtopic.php?t=973823
The issues Monkey and I were having was caused by a problem with sequence/native.