seb6@bton.ac.uk (Stratos) wrote in message news:<6d926bff.0308110414.98c0e4a@posting.google.c om>...
> Hello,
> I want to ask you a question about normalisation.
> I have got a long table with 8 fields(mandatory) that always store a
> value, and 20 fields(optional) than can either get a NULL or non-NULL
> value.
>
> Is it better to split this table up into two tables, one having all
> the
> mandatory fields and the other one having all the optional fields? Or
> is
> it fine to leave this table as it is?
> Thank you.

Are they logically separate entities? Are the optional fields
dependent on the mandatory fields? Lots of other similar question you
should ask on your way to designing the table or tables used to store
this information.

Then once you have the logical design done, you have to ask the hard
physical design questions such as: if the data is split into two
tables, will performance suffer for frequently used queries? Or is the
split useful in that backup and restore of data is easier? or...

IOW, with the vague question you asked, all we can say is IT DEPENDS!

HTH
ed