hibernate hql语句 插入数据到 oracle 问题！

插入方法
public void insert(TUserlog usrlog) throws Exception {
this.getHibernateTemplate().save(usrlog);
 }ApplicationContext ctx=new FileSystemXmlApplicationContext ("/WebRoot/WEB-INF/applicationContext.xml");
UserLogDAOImpl dao=(UserLogDAOImpl) ctx.getBean("iuserlogdaoimpl");
UserDAOImpl userdao=(UserDAOImpl) ctx.getBean("iuserdaoimpl");
    Timestamp tamp=new java.sql.Timestamp(new java.util.Date().getTime());
System.out.println(tamp);
String aa="TO_DATE('2010-11-25 11:51:46','YYYY-MM-DD HH24:MI:SS')";
String name="admin";
TUser usr=userdao.getUser(name);
TUserlog usrlog=new TUserlog(usr,name,usr.getUsrtype(),aa,usr.getUsrname()+"用户登陆成功");
dao.insert(usrlog);
报Hibernate operation: Could not execute JDBC batch update; SQL [insert into T_USERLOG (USRID, USRACCOUNT, USRTYPE, LOGTIME, LOGCONTENT, ULID) values (?, ?, ?, ?, ?, ?)]; ORA-01858: 在要求输入数字处找到非数字字符
; nested exception is java.sql.BatchUpdateException: ORA-01858: 在要求输入数字处找到非数字字符java.sql.BatchUpdateException: ORA-01858: 在要求输入数字处找到非数字字符 at oracle.jdbc.dbaccess.DBError.throwBatchUpdateException(DBError.java:458)
at oracle.jdbc.driver.OraclePreparedStatement.executeBatch(OraclePreparedStatement.java:3907)
at org.apache.commons.dbcp.DelegatingStatement.executeBatch(DelegatingStatement.java:294)
at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:57)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:174)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:226)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:136)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:274)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:730)
at org.springframework.orm.hibernate3.HibernateAccessor.flushIfNecessary(HibernateAccessor.java:394)
at org.springframework.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:367)
at org.springframework.orm.hibernate3.HibernateTemplate.save(HibernateTemplate.java:614)
at com.wprss.dao.impl.UserLogDAOImpl.insert(UserLogDAOImpl.java:18)
at com.wprss.dao.impl.UserLogDAOImpl.main(UserLogDAOImpl.java:30)
是这的问题String aa="TO_DATE('2010-11-25 11:51:46','YYYY-MM-DD HH24:MI:SS')";我如何才能应用TO_DATE函数呢  因为字段LOGTIME 是Timestamp(6）我怎么才能插入Timestamp类型的数据呢