Re: [OJB-developers] additional capabilities for report queries, OUTER JOIN ?

[Thomas M. <tho...@ho...>]

Hi Jakob

Jakob Braeuchi wrote:

> hi,
> 
> i just added additional capabilities for report queries to the cvs.
> ojb now supports groupBy and functions on columns for report queries.
> 
> crit = new Criteria();
> crit.groupBy("id");
> query = QueryFactory.newReportQuery(Person.class, crit);
> query.setColumns(new String[]{"id","name","vorname","sum(konti.saldo)"});
> broker.getReportQueryIteratorByQuery(query);
> // sum(konti.saldo) now handled correctly
> 
> this will execute the following sql:
> 
> SELECT tabPerson.id,tabPerson.name,tabPerson.vorname,sum(tabKonto.saldo)
> FROM tabPerson INNER JOIN tabKonto ON tabKonto.idPerson = tabPerson.id GROUP
> BY tabPerson.id
> 


cool !


> i need some help/input in the following issue:
> the query will only return id, name etc. for persons having at least one
> account. to retrieve data from persons without an account
> the join clause should be changed to "LEFT OUTER JOIN".
> 
> i'm now looking for a way to define the join type:
> 
> - should it be defined for criteria or query ?


IMO on the criteria level. The Query is mainly a container.


> - is there are way to automagically detect th join type ?


I'm not an expert in this area. But in all tools I have seen so far the 
user is responsible for setting the Join type.


> - is join type only an issue for report queries ?


I think this is also relevant for "normal" queries too.

Users will perform all kind of possible queries with full object materialization.

I'm well aware that it will be *very* difficult to provide Criteria 
based implementations for the complete SQL92 range !


cu,


Thomas