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skyknight
 Post subject: how to implement "CONNECT BY" using hibernate
PostPosted: Mon Apr 26, 2010 5:18 am 
Newbie

Joined: Sat Apr 12, 2008 12:59 pm
Posts: 10
hihi

I want to uses ORACLE "CONNECT BY" to obtain each level of tree structure, like:

A
|-B
--|-D
|-C
--|-E

The result should be: A = 1 and B,C = 2 and D,E = 3

Do I have another options to do this?

Thanks.
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hannehomuth
 Post subject: Re: how to implement "CONNECT BY" using hibernate
PostPosted: Mon Apr 26, 2010 10:08 am 
Newbie

Joined: Mon May 11, 2009 11:16 am
Posts: 13
I don't know if it possible by the original Hibernate (I use Hibernate JPA implementation) but can you create a Native query and provide the result class .

Something like this

em.createNativeQuery("Select * from table connect by prior something = someotherthing",TableEntity.class).getResultList();
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skyknight
 Post subject: Re: how to implement "CONNECT BY" using hibernate
PostPosted: Mon Apr 26, 2010 10:53 pm 
Newbie

Joined: Sat Apr 12, 2008 12:59 pm
Posts: 10
Thank you for your reply,hannehomuth.

but when I using native query, the program throws the NullPointerException, how can I solve this problem. (the query object is NOT NULL)


Code:
Query query = entityManager.createNativeQuery("SELECT group.*,level FROM GROUP group "+
                     "WHERE GROUP_TYPE = 'ACTIVE' START WITH (PARENT_GROUP_ID IS NULL) "+
                     "CONNECT BY PARENT_GROUP_ID = PRIOR GROUP_ID",GROUP.class);

log4jLogger.info("query: "+query);

List<GROUP> groups = query.getResultList();



Result:
Code:
INFO [http-8080-2] service.GroupAction (getGroups:36) - query: org.hibernate.ejb.QueryImpl@1a5db9c

...

Caused by: java.lang.NullPointerException
    at org.hibernate.loader.DefaultEntityAliases.intern(DefaultEntityAliases.java:157)
    at org.hibernate.loader.DefaultEntityAliases.getSuffixedPropertyAliases(DefaultEntityAliases.java:130)
    at org.hibernate.loader.DefaultEntityAliases.<init>(DefaultEntityAliases.java:76)
    at org.hibernate.loader.ColumnEntityAliases.<init>(ColumnEntityAliases.java:40)
at org.hibernate.loader.custom.sql.SQLCustomQuery.<init>(SQLCustomQuery.java:152)
at org.hibernate.engine.query.NativeSQLQueryPlan.<init>(NativeSQLQueryPlan.java:67)
at org.hibernate.engine.query.QueryPlanCache.getNativeSQLQueryPlan(QueryPlanCache.java:136)
at org.hibernate.impl.AbstractSessionImpl.getNativeSQLQueryPlan(AbstractSessionImpl.java:160)
at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:165)
at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:175)
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:67)
at test.GroupAction.getGroups(GroupAction.java:38)
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