Re: What databases have taught me
Date: Fri, 30 Jun 2006 21:23:46 GMT
> Bob Badour wrote:
>>Marshall wrote: >> >>>Mmmm, what I was trying to point out is that it is a somewhat >>>OOish idea to consider functions on a type as part of the >>>definition of that type. >>> >>>Given a set A, and a set B. >>>Given a function f: A -> B >>> >>>We would not *necessarily* consider f as part of the definition of A. >> >>I would. I wouldn't necessarily require all operations defined on a type >>be declared to the dbms, but the type is a set of values and a set of >>operations on those values.
> Are you saying you "would consider f as part of the definition of A"
> or are you saying you "would necessarily consider f as part of the
> definition of A."
That depends on whether A is a data type or a set. A data type is a set of values and the set of operations defined on those values. (Note that is data type as opposed to the myriad other uses of 'type'.)
> Other question:
> f: A, B -> C
> is f part of the defintion or A, or of B, or both? What about C?
> Just curious.
f is defined on all three A, B and C. Thus f is part of the definitions of three data types.
> PS. While you are at it, I need 500 words or more on
> "what I did during my summer vacation" by next Tuesday.
Hey! I know it sometimes seems otherwise, but this is comp.databases.theory and not comp.databases.do.my.homework.for.me! Received on Fri Jun 30 2006 - 23:23:46 CEST