Re: Counting propositions
Date: Mon, 14 Jun 2004 15:48:33 GMT
> "Laconic2" <laconic2_at_comcast.net> wrote:
>>"x" <x-false_at_yahoo.com> wrote:
>>> If tuples in a relational relation(ship) (or relvar) are
>>> propositions, what is the meaning of:
>>>select count(distinct *) as nr
>>>and the like ?
>> Before dealing with your question, we have to decode the intent
>> behind the wildcard.
>> In particular, when does the wildcard get expanded to the list of
>> all the columns? At compile time? at execution time?
>>It makes a difference.
If, like IBM DB2, you have an elaborate pre-compilation phase, then an automatic recompile would occur if the table had changed enough to invalidate the previous query plan - and adding a column would surely do that!
-- Jonathan Leffler #include <disclaimer.h> Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com Guardian of DBD::Informix v2003.04 -- http://dbi.perl.org/Received on Mon Jun 14 2004 - 17:48:33 CEST