i`m using hibernate 3.6.0.final and oracle 11g R1
when set hbm2ddl.auto to create mode it works
but when set hbm2ddl.auto to update mode and drop a column or a table from that schema:

Exception in thread "main" java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:58)
Caused by: org.hibernate.exception.SQLGrammarException: could not execute query at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:92)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.loader.Loader.doList(Loader.java:2536)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2276)
at org.hibernate.loader.Loader.list(Loader.java:2271)
at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:119)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1716)
at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:347)
at ir.saeed.db.SpringDBUtil.list(SpringDBUtil.java:97)
at ir.saeed.db.SpringDBUtil$$FastClassByCGLIB$$75c004c.invoke(<generated>)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:688)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:621)
at ir.saeed.db.SpringDBUtil$$EnhancerByCGLIB$$34c68088.list(<generated>)

at ir.saeed.db.TestClass.testRead(TestClass.java:33)
at ir.saeed.db.TestClass.main(TestClass.java:69)
... 5 more
Caused by: java.sql.SQLSyntaxErrorException: ORA-00904: "THIS_3_"."ID": invalid identifier

at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:440)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:396)
at oracle.jdbc.driver.T4C8Oall.processError(T4C8Oall.java:837)
at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:445)
at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:191)
at oracle.jdbc.driver.T4C8Oall.doOALL(T4C8Oall.java:523)
at oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:207)
at oracle.jdbc.driver.T4CPreparedStatement.executeForDescribe(T4CPreparedStatement.java:863)
at oracle.jdbc.driver.OracleStatement.executeMaybeDescribe(OracleStatement.java:1153)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1275)
at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3576)
at oracle.jdbc.driver.OraclePreparedStatement.executeQuery(OraclePreparedStatement.java:3620)

An earlier version of the documentation said that hibernate.hbm2ddl.auto=update was experimental.
I believe it is still so.

when i use another database on another machine it works
and when i use this machine and hbm2ddl.auto=create it works
but just when i use this machine and hbm2ddl.auto=update or hbm2ddl.auto=validate it does not work
i don`t know what is the problem
anybody can help me?????

i`ve changed my hibernate version to 4.1.3.FINAL
but not works with update and just works with create

what is doing hbm2ddl.auto=update????
i mean i want java code of that and sql that send to database

i`ve downloaded hibernate source code and set a breakpoint to Confuguration Class
and saw when hibernate going to create sql it think table already exist!!!!!
i saw my schema and the table is not in my schema and it is in another schema
i`ve checked my synonyms but synonym not exists
i`ve changed my db user`s roles and removed mgmt_user and dba
and problem resolved!!!!!!!!!!!
is than hibernate bug??????