Re: Define "flatten database" ?

"Dawn M. Wolthuis" <dwolt_at_tincat-group.comREMOVE> wrote in message news:ctdn9o$7sq$1_at_news.netins.net...
> "DA Morgan" <damorgan_at_x.washington.edu> wrote in message
> news:1106859773.807419_at_yasure...
> > silversw2000_at_yahoo.com wrote:
> >
> >> I had a database analyst interview yesterday on the phone, and the
> >> interviewer brought up the phrase: "I flattened the database".
> >>
> >> I did not obfuscate in replying to her thread, but was able to avoid
> >> having to know what she meant by that term.
> >>
> >> Can someone define "flatten database" for me, in 100 words or less (OK
> >> 500 words is fine).
> >>
> >> Fred Z.
> >>
> >
> > Denormalize.
>
> I would guess "normalize" is more likely. If the source dbms permits
> non-1NF structures, then the term "flatten" is sometimes used to mean that
> the data are put in1NF. Terms I might use as synonyms to "flatten" are
> "unnest", "explode", "normalize". It isn't quite the same as normalizing,
> however, because the embedded lists are not placed in a separate relation,
> but rather the "scalar" data are repeated in each row, while the list has
> one value per row. Reasons to flatten the structure would include a need
to
> use a SQL-92-based tool or pour the data into a single Excel worksheet.
>
> If the source dbms is a SQL-based product, then the user might still be
> dumping tag-delimited lists in as attribute values (we all know there are
> people who do that, right?) or even using some non-1NF capabilities of the
> particular RDBMS.
>
> Example:
>
> Start with:
>
> (12345,DeSmith,John,{jsmith_at_aol.com,JohnSmith_at_yahoo.com})
> (23127,Meador,Beth,{beth_meador_at_msn.com,bmeador_at_hotmail.com,btm_at_ibm.org})
>
> Then flatten it to get:
>
> (12345,DeSmith,John,jsmith_at_aol.com)
> (12345,DeSmith,John,JohnSmith_at_yahoo.com)
> (23127,Meador,Beth,beth_meador_at_msn.com)
> (23127,Meador,Beth,bmeador_at_hotmail.com)
> (23127,Meador,Beth,btm_at_ibm.org)
>
> That's my best guess. --dawn
>
> > --
> > Daniel A. Morgan
> > University of Washington
> > damorgan_at_x.washington.edu
> > (replace 'x' with 'u' to respond)
>
>

Dawn,

Flattening is DEnormalizing. Period. You have it backwards and twisted. It could be called Neo-normalizing. Received on Fri Jan 28 2005 - 19:15:09 CET