Re: EO inheritance clarification needed
Re: EO inheritance clarification needed
- Subject: Re: EO inheritance clarification needed
- From: Dev WO <email@hidden>
- Date: Wed, 13 Oct 2004 16:27:12 +0200
Thanks Ken,
Xavier,
The primary key needs to be in the sub-entity tables so they can be
related to the parent table.
Thanks, I'm starting to feel better;)
If you need to work with the data manually, I suggest triggers (does
MySQL have triggers?), or whatever other data integrity checking is
available, to make sure that you:
I don't want to work manually, I was just wondering how WO and EO
manage this to prevent the duplicated personID.
When I'll create a user or a client in my WO app, it'll will generate a
personID in the Person table and in the subentity by "magic"?
1) Always have a record in the person table with the same personID as
client or user
2) Never have a record in client and user with the same personID.
Ken
On Oct 13, 2004, at 9:41 AM, Dev WO wrote:
Hi,
I'm actually having some problem with EO and inheritance...
I've got an abstract class "Person" and 2 sub-entities "client" and
"user", I've got a personID attribute in Person which is the PK (and
so should be the PK for both client and user).
What I don't understand is when I generate the tables (on MySQL for
now), I get a Person table with a personID attribute, but I also got
a personID attribute in both the user and client tables...I don't
know if this is the normal behavior?
If I create a client and a user directly in MySQL, I can create them
with the same personID!?
So to summarize, does the attributes in the person table should be
"duplicated" in each table of the sub-entities (inside the DB)?
and if it's the case what is the mechanism that should prevent from
having 2 identical personID in the sub-entities?
Thanks a lot for helping me clarify this.
Xavier
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