Comments on: Cycling

By: Aketi Jyuuzou

Aketi Jyuuzou — Wed, 11 Feb 2009 03:02:24 +0000

Wow this is a great solution.
I have seen this DBMS_RANDOM usage in US-OTN-SQL-forum.
However I did not realize that “Connect by nocycle” can be emulated.

I have researched and tested that on Oracle9i.
Then I derived version like below

http://oraclesqlpuzzle.hp.infoseek.co.jp/8-43.html
Point is “and prior dbms_random.value != 1;” ,
Because dbms_random.value returns 0 or greater then 0 and lower then 1

By: Laurent Schneider

Laurent Schneider — Wed, 11 Feb 2009 01:02:25 +0000

Frank Zhou gave me the DBMS_RANDOM idea a long time ago, now I find a case to use it

By: Laurent Schneider

Laurent Schneider — Tue, 10 Feb 2009 06:02:51 +0000

good catch with != 1, it makes it 100% accurate instead of 99.999999999999999999999999999999999999%

By: Karl Reitschuster

Karl Reitschuster — Tue, 10 Feb 2009 05:02:42 +0000

with SYS_GUID() you even have no PL/SQL context switch in your SQL - Karl

SELECT PARENT,
Child
FROM Lsc_t
WHERE LEVEL = 50
CONNECT BY PARENT = PRIOR Child
AND LEVEL < = 50
AND PRIOR sys_guid() != sys_guid();

By: Laurent Schneider

Laurent Schneider — Tue, 10 Feb 2009 05:02:07 +0000

Yes, excellent

also possible with

and prior sys_guid() is not null

By: Brian Tkatch

Brian Tkatch — Tue, 10 Feb 2009 04:02:04 +0000

Why does this work?

By: Laurent Schneider

Laurent Schneider — Mon, 09 Feb 2009 10:02:44 +0000

well, in my humble opinion it is not supposed to work… It probably does not in oracle7 or 8 (anyone can check?)

it is very similar to the connect by without prior row generator
select * from dual connect by level

By: Brian Tkatch

Brian Tkatch — Mon, 09 Feb 2009 06:02:26 +0000

Dores PRIOR remeber the earlier calculated value instead of doing it a second time?