On May 14, 10:54 pm, gordonb.xi...@burditt.org (Gordon Burditt) wrote:
> >case 1) a table with many fields for storing some data, usually most
> >of them will be NULL because they are (and will ever be) unsused
>
> >case 2) a table with just 3 fields, but many entries, one for each
> >field i'd have used (not null) in case 1.
>
> This is problematical if the types of the fields aren't all the
> same.
>
> Consider also: case 3) a bunch of tables with 2 fields, the primary
> key, and the value of some column (not null). From case (1), you
> have a fixed list of these attributes. So use one table for each.
> If a value is NULL, leave out an entry in that table.
>
> This potentially costs disk space for storing repetitions of the
> primary key (and indexes), but you don't store anything for NULL
> values.
>
> Incidentally, you might consider whether values of NULL or 0 or
> something else is more appropriate. NULL might correspond to the
> stats of a game which hasn't been played yet; 0 might correspond
> to the stats of a game that is completed but without the player,
> say, batting in any runs. The difference might be significant if
> you want to use avg(rbi.score) to compute overall stats, where
> values of 0 (completed games) count in the average and values of
> NULL (unplayed-yet games) shouldn't.
>
> >which is better, in general?
>
> Which is better, Pepsi, rat poison, condoms, or beer? It depends on
> whether you're thirsty, rat-infested, horny, or sober.


Actually, as beer seems to remove the both the capacity and need to
either engage with or care about any of the above, I'd have to go with
beer.