Re: Is relational theory irrelevant?
Date: Wed, 19 Nov 2003 09:30:49 -0500
Message-ID: <bpfunr$dic$1_at_hanover.torolab.ibm.com>
The syntax is as follows:
At this point we limit the usage not to include views.
This is not because of a problem in the semantics. It's more a problem
of accepting that views can MODIFY SQL DATA by simply selsecting from
them. Something the standard (and most users I presume) reserve to
procedures.
SELECT .. FROM OLD TABLE(DELETE FROM ...)
OLD TABLE being the set of deleted rows
For UPDATE you have the choice of OLD TABLE and NEW TABLE (being the set
of rows as they are updated (after before triggers, etc...).
Consequently INSERT supports NEW TABLE only.
There are some more limits that we imposed since we are ahead of the
So what you can do is to perform a "relational workflow" where
intermediate sets are made persistent on disc by side-effect.
People like Paul like that kind of stuff for data cleansing :-)
Also you need such concepts in OLTP if you use surrogate keys produced
by the DBMS (such as sequences).
Example:
WITH del AS (SELECT * FROM OLD TABLE(DELETE FROM S))
I just wiped S and moved the data to T returning the number of rows moved.
Cheers
Serge
-- Serge Rielau DB2 SQL Compiler Development IBM Toronto LabReceived on Wed Nov 19 2003 - 15:30:49 CET