Excuse me, but I need to divert from the great themes of this moment:

1.- When a query is prepared and executed, what happens then? Does the
server push the records to the client or does the client pull the records
from the server? The issue has appeared many times and I'm left again with
the doubt. This question almost always is connected with closing/unpreparing
datasets in Delphi. If you add the BDE in the equation, things are more
difficult to trace.

2.- Why does Interbase always put the NULLs at the tail regardless of the
ORDER BY clause being ASC or DESC? Is this mandated in the SQL standard?

3.- Is the FOR/INTO statement atomic in a stored procedure? I mean if I do a
FOR SELECT X FROM T WHERE X <100 INTO :x
DO BEGIN
...
END
and inside the loop there's a clause that updates X on the same table and
another clause that adds records to the same table such that the new rows
have X<100, too; then
- Does the FOR pick the updated records that now have X<100 or miss the
updated ones that now have X>100 (and before they had X<100) or added
records that satisfy the WHERE clause?
- Is the result set of such construction calculated on advance, before the
FOR begins to run or the next record is searched and retrieved only on each
iteration of the FOR clause?
- If I invoke a selectable procedure from the client instead of having an
executable procedure that uses the FOR results internally (without returning
the rows to the client), is there any difference?

4.- What's the trick behind the idea that R/O result sets are sent with as
many records as possible inside a network packet whereas FOR UPDATE result
sets are sent with one record per network packet? What have I gained using
FOR UPDATE if live-recordsets in the server side are almost an illusion?
Usually, these live recordset are produced in the client side thanks to
buffering.

Thanks in advance.

C.
---------
Claudio Valderrama C.
Ingeniero en Informática - Consultor independiente
http://members.tripod.com/cvalde