Re: How to create Meaningful Primary Keys?

From: Alessio Giovanni Baroni (alessiogiovanni.baron..mail.com)
Date: Mon Feb 02 2009 - 09:40:40 EST

  • Next message: John Armstrong: "Re: How to create Meaningful Primary Keys? JUST SAY NO TO MEANINGFUL POINTERS!"

    But to have the full control on handling the primary keys, I always set the
    strategy option, else the keys are handled by cayenne.....

    2009/2/2 Pierre Lavignotte <pierre.lavignott..mail.com>

    > I don't think his question is about sequence usage but about selecting rows
    > with specific PK values...
    >
    > Cordialement,
    > Pierre Lavignotte
    > Ingénieur Conception & Développement
    > http://pierre.lavignotte.googlepages.com
    >
    >
    > On Mon, Feb 2, 2009 at 2:25 PM, Alessio Giovanni Baroni <
    > alessiogiovanni.baron..mail.com> wrote:
    >
    > > It's all ok. But, you are sure that in Entity screen, you are selected
    > > "Custom Sequence" on the "PK Generation Strategy"?
    > > If you do it, AND you add a filed relative to a pk column, you can
    > handling
    > > the keys, without the cayenne's control.
    > >
    > > Hi.
    > >
    > >
    > > 2009/2/2 Νίκος Παράσχου <niparas..mail.com>
    > >
    > > > First of all thank you for your replies.
    > > >
    > > > I have the following table:
    > > >
    > > > Vehicle (
    > > > plate_num CHAR(10) NOT NULL,
    > > > mixed_weight DOUBLE PRECISION NOT NULL,
    > > > type CHAR(30) NOT NULL,
    > > > manufacturer CHAR(20),
    > > > PRIMARY KEY (plate_num)
    > > > )
    > > >
    > > > In Cayenne Modeller I have the dbEntity "vehicle" with all the above
    > > > attributes (plate_num is check as PK). There is also the objEntity
    > > > "Vehicle" with all the above attributes except the PK (plate_num).
    > > >
    > > > I want to select the type of the vehicle with plate_num = "AHZ-4141".
    > > >
    > > > Could you please post some code samples? I have tried so many things
    > > > (with DataObjectUtils too) but still no success.
    > > >
    > > > Thank you,
    > > > Nikos
    > > >
    > > > Στις 02-02-2009, ημέρα Δευ, και ώρα 12:49 +0100, ο/η Pierre Lavignotte
    > > > έγραψε:
    > > > > Hi Nikos,
    > > > >
    > > > > If you need PK for all your tables, then maybe you need to generate
    > > them.
    > > > > But if you only need to use them for a couple tables then you should
    > > look
    > > > at
    > > > > DataObjectUtils class.
    > > > >
    > > > >
    > > > > Cheers,
    > > > > Pierre
    > > > >
    > > > > Cordialement,
    > > > > Pierre Lavignotte
    > > > > Ingénieur Conception & Développement
    > > > > http://pierre.lavignotte.googlepages.com
    > > > >
    > > > >
    > > > > On Mon, Feb 2, 2009 at 12:35 PM, Νίκος Παράσχου <niparas..mail.com>
    > > > wrote:
    > > > >
    > > > > > Hello,
    > > > > >
    > > > > > It is the first time I am using cayenne and I have some questions
    > > > > > regarding the primary keys.
    > > > > >
    > > > > > What I want to do is select some rows of a table where the PK has a
    > > > > > specific value. The problem is I can't access the PK. I can specify
    > > > > > qualifiers only with the non-PK columns. The PKs I am using have
    > some
    > > > > > meaning (they are not just numbers) so it is very important to be
    > > able
    > > > > > to use them.
    > > > > >
    > > > > > How can I add the PK to the fields of the Object Entities?
    > > > > >
    > > > > > In this page
    > > > http://cayenne.apache.org/doc20/primary-key-generation.html
    > > > > > the answer is to create a Meaningful Primary Key.
    > > > > >
    > > > > > How can I create Meaningful Primary Keys?
    > > > > >
    > > > > > Are there any security issues when using Meaningful Primary Keys?
    > > > > >
    > > > > > Thank you for your time,
    > > > > > Nikos
    > > > > >
    > > > > >
    > > >
    > > >
    > >
    >



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