Re: Setting up horizontal inheritance
Re: Setting up horizontal inheritance
- Subject: Re: Setting up horizontal inheritance
- From: Lachlan Deck <email@hidden>
- Date: Wed, 5 Nov 2008 06:29:46 +1100
On 05/11/2008, at 5:22 AM, Chuck Hill wrote:
On Nov 3, 2008, at 10:03 PM, Lachlan Deck wrote:
If you're mapping the parent entity to a table in the db - you've
got VI rather than HI.
No, VI it is a bit more involved than that.
Sure, I mean to say it's an incomplete VI.
I've never heard anyone mention before this thread that for HI your
parent entity needs to map to an external table for pk generation.
It does for FrontBase as the PK generation sequences as associated
with a physical table in FrontBase.
Why does there need to be pk generation for the parent entity at all?
I understood it to be completely abstract in that it is both abstract
and without an external table. The docs don't mention anything about
mapping to an empty table.
Note that for HI all the columns in the parent table are duplicated
in the children.
Sure.
Again, if your parent entity has an external table you're using VI.
Again, no. :-) Only if you have set up certain relationships and
flattened things. For HI each table contains a complete copy of the
attributes at that level.
That I knew.
with regards,
--
Lachlan Deck
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