Comments on: Question on Physical Files & Logical Files

By: Featured Member: YuVa47 - ITKE Community Blog

Featured Member: YuVa47 - ITKE Community Blog — Tue, 15 Mar 2011 06:02:48 +0000

[...] Question on physical files & logical files [...]

By: wilsonalano

wilsonalano — Wed, 09 Mar 2011 20:34:48 +0000

When you talk about “Primary Key” we can assume you”ve used the UNIQUE keyword when creating the first LF right?

If it’s true you can not violate the definition of the first LF. SO will not allow duplicate keys for the first LF no matter which file you use to add to (LF1, LF2 or direct to physical).

Wilson

By: yuva47

yuva47 — Wed, 09 Mar 2011 14:49:22 +0000

You can keep LF1 for what it was created for and you can of course keep LF2 as well.
Furthermore you can use both in the same and/or different programs.

YuVa

By: mvrkrishna

mvrkrishna — Wed, 09 Mar 2011 08:10:16 +0000

Hi Bigcat,

Sorry for the confusion created by me. It was un-intentional.

Based on the first LF1 (fld1 Primary key) , I added few records.
Now I created a second LF2 with composite primary key(fld1 & fld2 are primary keys). I add records through LF2. There is a possibility that i violate the very definition of LF1. How to encounter this? As per my requirement I need both the Logical files. I cannot delete the LF1.

By: bigkat

bigkat — Tue, 08 Mar 2011 13:20:04 +0000

was the second logical a replacement for the first (first: fld1 second: fld1, fld2, fld3) or was it an alternate lookup (first: fld1 second: fld2, fld3). If an alternate, there is no need to make a change. If a replacement, you could get rid of the first, or just recreate it with the composite key instead of adding the second logical. You do not need to use all of the keys in a logical, as long as you are using the first x keys (if logical fas keys of fld1, fld2, fld3 you can also use that logical to search by just fld1 or just fld1, fld2 -- you cannot search just by fld2 or just fld3 or just fld2, fld3)