[Year 12 IT Apps] MS Access - Calculated fields

Thu Mar 27 09:15:38 EST 2014

I think you're right. Having calculated fields defined in the tables takes us right away from a pure Codd style database. On the other hand Filemaker and, on DOS, DataPerfect did it for years. Convenience over purity?

My gut feeling is to stay away from calculated fields at this stage and use queries. Always best to start with best practice and then learn the tricks.

Laurie Savage

From: itapps-bounces at edulists.com.au [mailto:itapps-bounces at edulists.com.au] On Behalf Of Groves, Brett G
Sent: Wednesday, 26 March 2014 4:28 PM
To: Year 12 IT Applications Teachers' Mailing List
Subject: Re: [Year 12 IT Apps] MS Access - Calculated fields

Hi all - my 2 centimes

Can't really see the value of calculated fields in Access, maybe it is because I come at it from an SQL perspective but it represents fairly dodgy database practice methinks.

Can't really see how you can have true 3N with a calculated field stored in a table? Or have I got my head around it wrong?

I don't think I'll be including it at present; students should be using forms (and attendant query)  in datasheet view for such operations IMHO

Kind Regards,

Brett Groves
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From: itapps-bounces at edulists.com.au<mailto:itapps-bounces at edulists.com.au> [mailto:itapps-bounces at edulists.com.au] On Behalf Of Robert Timmer-Arends
Sent: Thursday, 13 February 2014 5:32 PM
To: Year 12 IT Applications Teachers' Mailing List
Subject: Re: [Year 12 IT Apps] MS Access - Calculated fields

Hello Damien

you may find this discussion useful

http://allenbrowne.com/casu-14.html
The update at the end covers Access 2010

Personally, the only situation I can see that might justify a value that is calculated once and then stored in a field (as Access 2010 seems to do), is where you need to squeeze every bit of performance out of the dbms that you can; for example, if you had a truck load of data that had to be pulled frequently, calculating a new value each time (either by query or on the fly like FileMaker) could slow retrieval down. But I can't see that happening on modern equip unless you have a lot of data, and/or maybe an overworked remote server?

Regards
Robert T-A
Brighton SC

----- Original Message -----
From: ATKINSON-BUCK, Damien<mailto:Damien.ATKINSON-BUCK at ivanhoe.com.au>
To: Year 12 IT Applications Teachers' Mailing List<mailto:itapps at edulists.com.au>
Sent: Thursday, February 13, 2014 1:38 PM
Subject: [Year 12 IT Apps] MS Access - Calculated fields

Hi folks,
            Just looking into Outcome 2 and looking at the 2010 version of MS Access. I hadn't noticed before, but you can now create a calculated field  in the table definitions. This means that not only does it do the calculation (duh) but stores that value too, so you no longer have to create a query to do that.
Now, I always stress to my cherubs that one of the primary reasons for making a database is to reduce the amount of space the data is going to take up. This new 'feature' does the reverse. Given hard drives are so cheap and our down databases are comparatively quite small, it doesn't really affect SAC scenarios......... but should we be teaching best practices or "The Way of the Access"? How do others feel about this?
Cheers
Damien

Damien Atkinson-Buck
Head of Learning Area: Technology/Arts
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