Question

I need to get the next value of a sequence twice in DB2 (version 9.1). Rather than executing the following twice:

SELECT nextval FOR schema.sequence AS id
FROM dual

I would like to do something like:

SELECT nextval FOR schema.sequence AS id1,
       nextval FOR schema.sequence AS id2
FROM dual

Except the above only increments it once:

ID1         ID2        
----------- -----------
        643         643

  1 record(s) selected.

Am I forced to just query twice, or is there a way to increment it twice in 1 query?

Answer 1

This is a a little complex, but it works (I verified by running it in DB2 v.9).

WITH GENERATED (KEYVAL) AS
(select 1
   from sysibm.sysdummy1
  UNION ALL
 SELECT KEYVAL + 1
   FROM GENERATED
  WHERE KEYVAL < 2)        -- how many you want

SELECT KEYVAL AS INCREMENT_NUMBER, NEXTVAL FOR schema.sequence
  FROM GENERATED;

This is some of my favorite code, and it is recursive SQL. You can do it without the sequence object, and it will just generate several rows of numbers. I use this sometimes to insert rows of generated test data.