Re: functional dependencies
From: Marshall Spight <mspight_at_dnai.com>
Date: Sun, 15 Jun 2003 16:40:36 GMT
Message-ID: <8k1Ha.1005196$Zo.227474_at_sccrnsc03>
> I would also like to post another question at this point.
> Can any one give me an example of a relation where we have a
> trivial FD?
> A trivial FD is of the form
> A -> B where B is a subset of A.
Date: Sun, 15 Jun 2003 16:40:36 GMT
Message-ID: <8k1Ha.1005196$Zo.227474_at_sccrnsc03>
"Rohan Hathiwala" <rp_hathiwala_at_yahoo.com> wrote in message news:3ec1cded.0306102221.2d9b2852_at_posting.google.com...
>
> I would also like to post another question at this point.
> Can any one give me an example of a relation where we have a
> trivial FD?
> A trivial FD is of the form
> A -> B where B is a subset of A.
Sure. Let's say we have a table of unique integers Z. For fun, let's say it contains three rows: Z = 1, Z = 2, and Z = 3.
Now A, B are sets of columns. Here, A = {Z}, and B = {Z}. B is functionally dependent on A. B is a subset of A. Easy.
Marshall Received on Sun Jun 15 2003 - 18:40:36 CEST