Re: Creating Compound PKs

From: John Armstrong (siberia..mail.com)
Date: Mon Jun 04 2007 - 02:52:24 EDT

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    Yes ID is a unique PK but I also want to enforce uniqueness across the
    NAME/SERVERID columns (A given Name can only be valid once per
    serverid).

    I can enforce it unique in the database but I was thinking that
    Cayenne may have a more elegant way of managing it without having to
    manually apply the database changes after schema creation. To me that
    screamed 'New compound PK'.

    How do you create compound PK's in Cayenne? I'm still using the
    Modeller so I may have to edit the XML natively?

    Thanks Andrus
    John-

    On 6/3/07, Andrus Adamchik <andru..bjectstyle.org> wrote:
    > Hmm... is this even a PK generation question? I understand that "id"
    > is a unique PK already? Is there a need to define name/serverid as a
    > part of PK as well? I mean you can (and Cayenne will support it), but
    > what's the point. Maybe instead you can define a UNIQUE constraint on
    > those two columns in your table?
    >
    > Andrus
    >
    >
    > On Jun 4, 2007, at 9:25 AM, John Armstrong wrote:
    >
    > > Yes, sorry misplaced that bit of important information.
    > >
    > > ImapServer
    > > account
    > > id
    > > password
    > > serverip
    > >
    > > Tx
    > > John-
    > >
    > >
    > >
    > > On 6/3/07, Andrus Adamchik <andru..bjectstyle.org> wrote:
    > >> Hi John,
    > >>
    > >> A question - is "serverid" a foreign key to another table by any
    > >> chance?
    > >>
    > >> Andrus
    > >>
    > >>
    > >> On Jun 4, 2007, at 9:09 AM, John Armstrong wrote:
    > >>
    > >> > Does Cayenne allow for the creation of a compound PK? I searched
    > >> the
    > >> > archives and google more generally and could only find hints at
    > >> this.
    > >> > The docs did not clarify either (although it was also hinted at. .I
    > >> > think, its a bit late :) ).
    > >> >
    > >> > My table looks like this:
    > >> >
    > >> > id
    > >> > name
    > >> > serverid
    > >> > status
    > >> > enabled
    > >> >
    > >> > I need to create a compound PK on name/serverid that will maintain
    > >> > uniqueness across these segments.
    > >> >
    > >> > My fallback is to create a validation that checks these before
    > >> commit
    > >> > but my normal route in a non-ORM context is to let the DB
    > >> enforce it
    > >> > and catch it there.
    > >> >
    > >> > Thanks!
    > >> > John-
    > >> >
    > >>
    > >>
    > >
    >
    >

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