How to use @Subselect in Hibernate

Question

I am trying to work on an example for @Subselect using Hibernate documentaion.

I have created entities for Bid and Item as follows:

@Entity
public class Bid {
    @Id
    private int id;
    @Column(name="item_id")
    private int itemId;
    @Column
    private int amount;
//getters & setters
}


@Entity
public class Item {
    @Id
    private int id;
    @Column
    private String name;
//getters and setters
}

I have inserted some records in database tables for Bid and Item. Now I have created another entity to test the @Subselect as:

@Entity
@Subselect("select item.name name, max(bid.amount) amount, count(*) count " + "from item "
        + "join bid on bid.item_id = item.id " + "group by item.name")
@Synchronize({ "item", "bid" })
// tables impacted
public class Summary {
    @Id @GeneratedValue
    private int id;
    @Column
    private String name;
    @Column
    private String amount;
    @Column
    private String count;
//getters & setters
}

I am new to Hibernate so trying to create a sample program to test the feature of @Subselect.

public class AppTest {
    public static void main(String[] args) {
        Session session = HibernateUtil.getSessionFactory().getCurrentSession();
        session.beginTransaction();

        //createItemsAndBids(session);
        Summary summary = new Summary();
        session.save(summary);

        session.getTransaction().commit();
        HibernateUtil.getSessionFactory().close();
    }

When I run this program I am getting below errors:

Hibernate: select hibernate_sequence.nextval from dual Hibernate: insert into ( select item.name name, max(bid.amount) amount, count(*) count from item join bid on bid.item_id = item.id group by item.name ) (amount, count, name, id) values (?, ?, ?, ?) Aug 10, 2014 1:24:31 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions WARN: SQL Error: 904, SQLState: 42000 Aug 10, 2014 1:24:31 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions ERROR: ORA-00904: "ID": invalid identifier

Caused by: java.sql.SQLSyntaxErrorException: ORA-00904: "ID": invalid identifier

Please help me how to test the feature of @Subselect of hibernate

Also I tried using HQL, even then I am getting same error:

public class AppTest {
    public static void main(String[] args) {
        Session session = HibernateUtil.getSessionFactory().getCurrentSession();
        session.beginTransaction();

        //createItemsAndBids(session);
        Query query = session.createQuery("from Summary");
        List result = query.list();
        System.out.println(result);

        session.getTransaction().commit();
        HibernateUtil.getSessionFactory().close();
    }

Update: The error I am getting with this HQL query is :

Aug 11, 2014 12:35:07 AM org.hibernate.tool.hbm2ddl.SchemaUpdate execute
INFO: HHH000232: Schema update complete
Hibernate: select summary0_.id as id1_2_, summary0_.amount as amount2_2_, summary0_.count as count3_2_, summary0_.name as name4_2_ from ( select item.name name, max(bid.amount) amount, count(*) count from item join bid on bid.item_id = item.id group by item.name ) summary0_
Aug 11, 2014 12:35:07 AM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
WARN: SQL Error: 904, SQLState: 42000
Aug 11, 2014 12:35:07 AM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
ERROR: ORA-00904: "SUMMARY0_"."ID": invalid identifier

Exception in thread "main" org.hibernate.exception.SQLGrammarException: could not extract ResultSet
    at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:80)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:91)
    at org.hibernate.loader.Loader.getResultSet(Loader.java:2065)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1862)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1838)
    at org.hibernate.loader.Loader.doQuery(Loader.java:909)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:354)
    at org.hibernate.loader.Loader.doList(Loader.java:2553)
    at org.hibernate.loader.Loader.doList(Loader.java:2539)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2369)
    at org.hibernate.loader.Loader.list(Loader.java:2364)
    at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:496)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:387)
    at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:231)
    at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1264)
    at org.hibernate.internal.QueryImpl.list(QueryImpl.java:103)
    at org.hibernate.tutorials.hibernate5.one.AppTest.main(AppTest.java:19)

Answer 1

Summary is supposed to be an immutable, read-only entity. It makes no sense to create a Summary. What you can do is create Items, create Bids, then query Summary instances.

EDIT: the error is pretty clear. Look at the generated SQL:

select summary0_.id as id1_2_, summary0_.amount as amount2_2_, summary0_.count as count3_2_, summary0_.name as name4_2_ from ( select item.name name, max(bid.amount) amount, count(*) count from item join bid on bid.item_id = item.id group by item.name ) summary0_

and at the error:

ORA-00904: "SUMMARY0_"."ID": invalid identifier

Your entity defines an id property:

@Id @GeneratedValue
private int id;

but the query of the Subselect annotation doesn't select any property named id:

select item.name name, max(bid.amount) amount, count(*) count from item 
join bid on bid.item_id = item.id 
group by item.name

You probably want your query to be

select item.id id, item.name name, max(bid.amount) amount, count(*) count from item 
join bid on bid.item_id = item.id 
group by item.id, item.name

Also note that the @GeneratedValue annotation doesn't make sense, since you can't persist instances of Summary, and Hibernate will thus never have to generate an ID for this entity.