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From Dennis Riedel <dennis_rie...@web.de>
Subject Query on multiple tables
Date Mon, 08 Aug 2005 08:10:30 GMT
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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