IDS Forum

RE: Relationship btw Tables?

Posted By: Martin Fuerderer
Date: Thursday, 1 April 2004, at 1:26 p.m.

In Response To: Relationship btw Tables? (Michael)

Hi,

your more detailed description of this confirms what I was afraid it would
be ...

Of course it is possible to implement all sorts of logic in the client
application,
even though the database could handle it. Triggers, stored procedures,
constraints
(including referential constraints) have been around in OnLine (the
predecessor to IDS)
and IDS itself for a long time. Therefore I can just now think of only
three explanations for
implementing such logic in the client application instead of using the
servers functionality:

- the application is very old, from a time where such functionality was
not fully
available in the server. (But I think in that case we would be talking
about 10+ years).

- the application was written to be independent of the database server
product.
Some of the really good stuff on offer in servers is not really
standardized.
Therefore by moving all such logic to client application you would be
more
portable. But then again you could almost use C-ISAM instead of a full
blown
database server ...

- job security on the side of the application developers.
Obviously it didn't help that much in this category.

This is a really wide topic you're looking at. From what you tell I think
a lot can be done,
i.e. a lot of the logic now in the client application can be off-loaded to
the server to be
handled there much cleaner and easier.
However, since you say you do not yet have much experience with IDS, I
think it is not
really possible to work out a good database design via news-group help ...
:-(

I'm not sure what trainings are on offer for IBM Informix products in your
geography.
There used to be a couple of trainings available on such topics (like
database design,
application development using ESQL/C, even "Triggers" had its own training
I think).

Another possibility (and probably faster) might be to get a knowlegable
and experienced
consultant (from IBM or an IBM Partner) to help you (not for free though
...) ?

Regards,
Martin
--
Martin Fuerderer
IBM Informix Development Munich
Data Management Solutions




"Michael" <michael@mikeymall.com>
01.04.2004 16:12

To
Martin Fuerderer/Germany/IBM@IBMDE
cc
<forum.subscriber@iiug.org>, <ids@iiug.org>
Subject
RE: Relationship btw Tables? [2772]






Hi,

Actually I used the "-ss" option when I did the schema. Can I confirm with
you that if I used "-ss" it should actually list out everything? Including
relationship constraints, etc?

The problem with the current database is that I don't seem to see any
relationship connection. And they have 500 over tables.. so you can
imagine
the mess. I believe like some of the people had said, they're using the
application to "relate" the tables. But won't that be a mess? I don't
know,
coz usually I always create the relationship in the database. What if I
connect directly to the database, added a record in the MAIN table and
some
records in the SUB table. And if I delete that record in the MAIN table
and
forgot about the records in the SUB table, wont there be redundant data?

Right now because the client had a bad experience with the previous
developer and remove them from the development and found us instead.
Although the previous developer had thick manuals describing the tables
but
its not detailed and didn't state the relationship. So you can imagine we
got to look through the application source codes and the tables and relate
them through instinct. And its my first time using Informix with UNIX, so
I
were just puzzled with all the questions. Thus, I apologise if I irritate
any users for my novice questions.

Regards,
Michael


-----Original Message-----
From: Martin Fuerderer [mailto:MARTINFU@de.ibm.com]
Sent: Thursday, April 01, 2004 9:21 PM
To: Michael
Cc: forum.subscriber@iiug.org; ids@iiug.org
Subject: Re: Relationship btw Tables? [2772]

Hi,

there's "delete on cascade".
I'm not aware of anything like "stop on delete" or "cascade on update",
etc.

However, with IDS you have "Triggers". With these you can implement and
customize much more.
Since they offer realization of quite complex things, I recommend reading
the manual (probably the three SQL manuals (Tutorial, Syntax, Reference).

Regarding dbschema you might want to check that you used the "-ss"
option. It will add Informix IDS specific things to the created
statements,
and some things you're looking for might be just these ...

Regards,
Martin
--
Martin Fuerderer
IBM Informix Development Munich
Data Management Solutions




"Michael" <michael@mikeymall.com>
Sent by: forum.subscriber@iiug.org
01.04.2004 08:23

To
ids@iiug.org
cc

Subject
Relationship btw Tables? [2772]






is it possible to set relationship constraints (stop on delete or cascade
on update, etc) btw tables in informix?

because recently we took over some informix database in a unix box.
There's about 500 over tables in the database and when i did a schema, i
noticed there's no relationship constraints betw a "MAIN" table and its
"SUB" tables. So i was wondering if its because informix does not have
this feature?

I was using mssql and its common practise to set such relationship, thus i

was puzzled when i saw this.

Thanks

Messages In This Thread

• Relationship btw Tables?
  Michael -- Thursday, 1 April 2004, at 1:23 a.m.
  • RE: Relationship btw Tables?
    NormaJean.Sebastian@tellabs.com -- Thursday, 1 April 2004, at 8:24 a.m.
  • Re: Relationship btw Tables?
    ART KAGEL, BLOOMBERG/ 499 PARK -- Thursday, 1 April 2004, at 8:43 a.m.
    • Re: Relationship btw Tables?
      Jonathan Leffler -- Thursday, 1 April 2004, at 12:27 p.m.
  • Antw: IDS: Relationship btw Tables
    Andreas.KUTSCHE@spar.at -- Thursday, 1 April 2004, at 11:57 a.m.
  • RE: Relationship btw Tables?
    Martin Fuerderer -- Thursday, 1 April 2004, at 1:26 p.m.
    • Re: RE: Relationship btw Tables?
      - MICHAEL -- Thursday, 1 April 2004, at 7:19 p.m.

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