Re: Layout Hell

From: LX-i (lxi0007_at_netscape.net)
Date: 07/18/04 

Date: Sat, 17 Jul 2004 22:31:19 -0500

Mike wrote:
>>I was with you 'til the last one - you can have multiple-field PK's in
>>Access (I believe at least as far back as version "97")...
>
>
> I said that poorly. You can't have multiple primary key fields that you
> treat as one field or one name - like a group level name is the key which
> consists of many fields underneath it - at least as far I know. If you
> have 3 columns F1, F2, F3 as primary keys you can't say F-All is the key?
>
> Record Key is F-All.
> 05 F-All.
> 10 f1 pic x.
> 10 f2 pic x.
> 10 f3 pic x.

Right. But, instead of assembling the pieces to an intermediary field
and then doing a read based on 1 key, you'd just use those pieces in the
select statement...

select * from f_table where (f1 = [value for f1] and f2 = [value for f2]
and f3 = [values for f3])

...whereas, in the COBOL file equivalent, you'd say...

move [value for f1] to f1
move [value for f2] to f2
move [value for f3] to f3
read f-file record

. You're still dealing with the pieces, just not on the actual
retrieval command.

SQL is a different beast from an indexed file (of course, you seem to
know enough about SQL to know that... ;> ) And, although Access does
its best to hide stuff, you can still create indexes and primary keys to
help speed things up (and maintain data integrity). My biggest grip
with Access is when you have more than one user hitting it - in my
experience, it's locking mechanism doesn't seem to be designed well for
multi-user applications. 

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