It is not wrong to check constrains. I just don't think it worth
creating a DB layer to do some ineffective constrains checking. (I
think that is what SQL referential integrity is for if you really needs
it). You own DB layer can of course be customized to suit your need,
the question is it worth it. Flexibility is good, but it comes with a
price.
-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of chris beck
Sent: Tuesday, October 02, 2007 4:36 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: RE: MVC in RPG?
So is it wrong to use check constraints? This is validation at the DB
level?
Lim.Hock-Chai@xxxxxxxxxxxxxxx 10/2/2007 4:23:49 PM >>>
I don't see how one can easily implement business logic at the DB layer.
When a program writes/update a record in a file, the values in this
record will likely to require all type of records from other files to
get validated correctly. It is a lot better to implement business logic
at a business logic layer, as Aaron mentioned in previous email.
-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Wilt, Charles
Sent: Tuesday, October 02, 2007 4:14 PM
To: RPG programming on the AS400 / iSeries
Subject: RE: MVC in RPG?
I just disagree with creating DB layer that basically doing about the
same thing as RPG's chain/read/setll and forces all developer to have
to use it to access file.
This is the whole point. Developers are forced to used the predefined
static interfaces. Thus, it's very easy to ensure that the files are
being accessed properly and that all business rules are enforced.
You don't have to look through every line of code to make sure that a
developer hasn't done something wrong when writing to the DB directly.
Charles
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