Comments for Laurent Schneider

Comment on where c not in (:b1, :b2, … , :b9999) by Martin Preiss

Martin Preiss — Thu, 18 Mar 2010 13:34:36 +0000

A fine solution. I think, that’s one of De Morgan’s laws: NOT (P OR Q) = (NOT P) AND (NOT Q)?

But having written queries with IN-Lists of more than 1000 elements in the past, I think there are good reasons for ORA-01795 - because it’s a pain to read these queries …

And I think there are also good reasons to be cautious with NOT IN at all because NOT IN (NULL) may lead to unpleasant effects …; and if my memory serves me well the CBO has it’s problems to compute the fitting prohability for IN-(or NOT IN-)lists.

Regards
MP

Comment on where c not in (:b1, :b2, … , :b9999) by John Flack

John Flack — Thu, 18 Mar 2010 13:20:03 +0000

There is a better way than using a temporary table, but it takes a little doing to set up. First, create a nested table type:
CREATE TYPE vc_arraytype AS TABLE OF varchar2(4000);
Now you can load a variable of that type with values - here’s a PL/SQL example, but you can also do this with an array in an embedded SQL environment - C, Java …
DECLARE
my_list VC_ARRAYTYPE;
BEGIN
FOR i IN 65..74 LOOP my_list(i):=CHR(i);END LOOP;
FOR my_rec IN (SELECT * FROM my_table WHERE my_column IN my_list) LOOP
— do stuff with my_rec
NULL;
END LOOP;
END;
If you are using C or some language other than PL/SQL, you may need to use the CAST function to cast your array as a VC_ARRAYTYPE in the WHERE clause.

Comment on KEEP DENSE_RANK versus ROW_NUMBER() by Jeff Moss

Jeff Moss — Fri, 12 Mar 2010 21:43:07 +0000

Nice post…useful stuff.

A bit more evidence on the following post on my blog and a bit more discussion…

http://www.oramoss.com/blog/?p=157

Cheers
Jeff

Comment on Happy New Year 2010 by Kamran Agayev

Kamran Agayev — Sun, 07 Mar 2010 15:46:35 +0000

Hi Laurent. From today, I’ve started using html support. The flash GUI really drives me nuts!

Comment on OCM preparation by Laurent Schneider

Laurent Schneider — Fri, 05 Mar 2010 23:31:40 +0000

learning the syntax by heart helps. definitely.

no search function in the exam

Comment on the sqlplus settings I like by Mark

Mark — Fri, 05 Mar 2010 20:04:21 +0000

Just used the “SET LONG” to export entire clob field in sqlplus. Thanks for the great tip!

Comment on OCM preparation by Paresh

Paresh — Thu, 04 Mar 2010 20:10:20 +0000

Hi,

I have a question about OCM exam. I understand that it is not advisable to ‘discover’ things during the exam. At the same time I don’t think it is possible to remember all the syntax (diagrams) no matter even if one has years of experience. Is the search function (*not* google search ;-)) available in reference documentation provided during the exam?

Thanks,
Paresh

Comment on on analytics and superaggregation by Laurent Schneider

Laurent Schneider — Mon, 01 Mar 2010 07:54:24 +0000

Thanks for the info… smart move from IBM I suppose!

Comment on on analytics and superaggregation by Gary

Gary — Sun, 28 Feb 2010 22:19:04 +0000

They licensed a bunch of functionality from EnterpriseDB, which added Oracle-like functions to Postgres.

http://www.enterprisedb.com/solutions/ibm_db2_license.do

Comment on on analytics and superaggregation by Laurent Schneider

Laurent Schneider — Sun, 28 Feb 2010 20:33:54 +0000

I will get a try, Serge mentioned the DB2_COMBATIBLITY_VECTOR=ORA setting so that I can also use plsql