Re: first normal form

>> Unfortunatelly I lost both my 3-rd and 7-th editions of C Date's
book, .. <<

Loaned them to friends? <G>

>> A definition of 1NF says that you cannot have arrays or repeating
groups in a column. <<

That was Codd's original definition, as I recall ...

>> I also remember that Date had a definition based on atomicity (which
clarifies the case presented). <<

That was Date's later definition. but you will see this called as Zero Normal Form sometimes, since techncially, the child_1, child_2, etc. columns are atomic, but the subset of columns is a repeated group of the same kind of entities.

>> repeating groups means something like: SocInsNumber(PK), Name,
Child1Name, Child2Name, Child3Name, etc.. arrays mean: lastName,firstName,wholeName(which is lastName||firstname) <<

I agree about repeating groups, but it is usually within a single field, like we useed to do in Cobol in the Dark Ages. Arrays are repeated groups which can be refrenced by position number. The concatenated string is non-atomic because each of its pieces has meaning in the data model by itself.

--CELKO-- Sent via Deja.com http://www.deja.com/
Before you buy. Received on Fri Mar 31 2000 - 00:00:00 CEST