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From Dennis Riedel <>
Subject Re: Query on multiple tables
Date Mon, 08 Aug 2005 08:12:49 GMT
Wrong maillist. Copied the wrong address.

Dennis Riedel wrote:

> Hello
> I am new to OJB and asking myself, how to query multiple tables using 
> the persistenceBroker.
> I cannot follow the example given on the OJB Query Page, I don`t 
> understand it.
> I have three tables and all contain one column 'area_id'. I want to 
> find all entries in all tables containing a specific area_id, e.g. '2'.
> So I think joining them would be the idea.
> When I expect one resulting object of that query (there can be only 
> one result, that is a fact), of which type will this be?
> I workd with DAO Classes to recieve a special object or a collection 
> of special objects.
> But how is it, when I query on three tables, representing three 
> different objects? Do I need a wrapper? Should these three objects 
> implement the same interface to 'encapsulate' or 'wrap' the resulting 
> object?
> With my actual knowledge I would query each table with its DAO but 
> that would be three queries to get the result.
> I want one query.
> Thanks for any support on querying multiple tables.

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