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Query not returning the type of Object I expect

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davidrocks

Post subject: Query not returning the type of Object I expect

Posted: Wed Feb 11, 2009 4:14 pm

Newbie

Joined: Sun Mar 27, 2005 1:22 pm
Posts: 15

I have an object(table) UserBetCompetitionHistory(user_bet_competition_history ), that in turn holds an object called User and a double value called ODDS_WON

TO get all my UserBetCompetitionHistory objects I use

Quote:

Query query = session.createQuery( "from UserBetCompetitionHistory as compHist" ) ;

And that works fine but I want to change it to this (working correctly) mySQL query in..

Quote:

SELECT user_id , SUM(odds_won) FROM user_bet_competition_history group by user_id ;

Quote:

Query query = session.createQuery( "select user , SUM(ODDS_WON) from UserBetCompetitionHistory as compHist" ) ;

but get..

Quote:

java.lang.NullPointerException
at org.hibernate.dialect.Dialect$3.getReturnType(Dialect.java:102)
at org.hibernate.hql.ast.util.SessionFactoryHelper.findFunctionReturnType(SessionFactoryHelper.java:382)
at org.hibernate.hql.ast.tree.AggregateNode.getDataType(AggregateNode.java:21)
at org.hibernate.hql.ast.tree.SelectClause.initializeExplicitSelectClause(SelectClause.java:143)
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)

But the really weird thing is that if I use this line

Quote:

Query query = session.createQuery( "select compHist.user from UserBetCompetitionHistory as compHist" ) ;

I get a collection of User objects rather than a collection of UserBetCompetitionHistory objects when I start the HQL query at "from.

I realise that the SUM does not work becasue the query is not returning UserBetCompetitionHistory objects. Can anyone help me by telling me why an arraylist of User objects is being returned and hopefully can anyone help me to get the SUM working?

Thanks.

Hibernate version: 3.0

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davidrocks

Post subject:

Posted: Wed Feb 11, 2009 5:11 pm

Newbie

Joined: Sun Mar 27, 2005 1:22 pm
Posts: 15

hmm, i think I have got a bit further with

Quote:

Query query = session.createQuery( "select new UserBetCompetitionHistory( user , odds_won ) from UserBetCompetitionHistory as" +
" compHist" ) ;

Not working yet but i'll give it another flog.

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nordborg

Post subject:

Posted: Wed Feb 11, 2009 5:32 pm

Expert

Joined: Wed Mar 03, 2004 6:35 am
Posts: 1240
Location: Lund, Sweden

Quote:

Can anyone help me by telling me why an arraylist of User objects is being returned

Well, your query do say 'select compHist.user...' which is a User object, so it is very expected that this should return a list of User objects. There are lots of examples in the Hibernate documentation http://www.hibernate.org/hib_docs/v3/re ... elect.html

For the query, when you need separate sum() for each user you also need to 'group by' the user. Try something like:

Code:

select user, sum(compHist.ODDS_WON) from UserBetCompetitionHistory as compHist 
join compHist.user as user
group by user.id, .... <-add ALL user properties as a comma-separated list

See http://www.hibernate.org/hib_docs/v3/re ... uping.html for more information about the group by clause.

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