RE: YADSQ. yet another dumb subclass question

Thomas,

First off, you have to make sure that every sub-entity of BARCODE has a =
single '=3D' qualifier in the Qualifier field like CATEGORY =3D 'ABC'.  =
You should also make sure the super entity (BARCODE itself), has a =
qualifier that will not match anything, like CATEGORY =3D 'NONE'.

That should result in a single query.  Can you tell us how you're =
fetching the BARCODE EO?

Ken

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Thomas Ganter
Sent: Friday, March 11, 2005 9:34 AM
To: [email protected]
Subject: YADSQ. yet another dumb subclass question


Hello world,=20

perhaps I again answer my own question, but please confirm that I am not =
overseeing something here:=20

I want to add barcode support for a system that supports multiple types =
of products that have completely different attributes and data models =
(and thus are stored in completely different tables).=20

Barcodes are supposed to be stored in a database table, called BARCODE.=20

BARCODE is (besides the barcode information) having two fields, one =
being PRODUCT_CATEGORY and the other one being PRODUCT_ID.=20

Now, the Idea was to have subclasses of BARCODE, one for each category =
(using appropriate, disjoint qualifiers) that, in turn, each have a =
relationship to another product main description table (or whatever) =
using the PRODUCT_ID as a foreign key.=20

Ideally, I then can retrieve one record from "BARCODE" which will by its =
Java class already know its type and the to_product() relationship will =
automatically retrieve the correct data.=20

Unfortunately, I cannot get this to work properly (i.e. without multiple =
round trips to the database just for one fetch specification).=20

Is this not possible, or am I simply missing something here?

Greetings,=20

- Thomas

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