Hi i was having a problem same as:
http://72.5.124.102/thread.jspa?threadID=5387518&messageID=10716811
I followed the post and change the code. But now the exception changes to:
Caused by: java.lang.IllegalStateException: No data type for node: org.hibernate.hql.ast.tree.AggregateNode
\-[AGGREGATE] AggregateNode: 'max'
\-[IDENT] IdentNode: 'topic_id' {originalText=topic_id}
at org.hibernate.hql.ast.tree.SelectClause.initializeExplicitSelectClause(SelectClause.java:145)
at org.hibernate.hql.ast.HqlSqlWalker.useSelectClause(HqlSqlWalker.java:705)
at org.hibernate.hql.ast.HqlSqlWalker.processQuery(HqlSqlWalker.java:529)
at org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:645)
at org.hibernate.hql.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:281)
at org.hibernate.hql.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:229)
at org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:228)
at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:160)
at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:111)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:77)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:56)
at org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:72)
at org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:133)
at org.hibernate.impl.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:112)
at org.hibernate.impl.SessionImpl.createQuery(SessionImpl.java:1623)
at table.Topic.TopicDAO.findMaxId(TopicDAO.java:145)
at td.Course.RegesterCourse.regester(RegesterCourse.java:149)
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.apache.el.parser.AstValue.invoke(AstValue.java:152)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276)
at com.sun.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:68)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
... 28 more
.JAVA
This is the only line i added in my method and exception changed to the one i gave above
context = FacesContext.getCurrentInstance(); //to avoid java.lang.IllegalStateException