Oracle-L: RE: SQL Brain Teaser Challenge

From: <Jared.Still_at_radisys.com>
Date: Wed, 06 Nov 2002 11:30:40 -0800
Message-ID: <F001.004FD024.20021106113040@fatcity.com>

I'm seeing some very strange results using _new_connect_by_enabled = true

alter session set "_new_connect_by_enabled" = true;

  1 SELECT *
  2 FROM (SELECT * FROM treenode ORDER BY parentid, nodeorder)   3 START WITH parentid=0
  4 CONNECT BY PRIOR ID = parentid
  5* order by parentid, nodeorder
11:22:48 rsysdevdb.radisys.com - jkstill_at_dv01 SQL> /

ID PARENTID NODEORDER DESCRIPTION
---------- ---------- ---------- --------------------

         1          0          0 top folder
         9          1          0 1st subfolder
         2          1          1 2nd subfolder
         4          2          1 folder 2 item 1
         3          2          2 folder 2 item 2
        10          3          1 nested folder2.2.1
        11         10          2 nested folder2.2.2
         6          2          3 folder 2 item 3
         7          1          2 3rd subfolder
         5          7          0 folder 3 item 1
         8          7          1 folder 3 item 2

11 rows selected.

11:22:49 rsysdevdb.radisys.com - jkstill_at_dv01 SQL>

These are the expected results. Now I comment out the 'FROM' clause, and add a
new FROM and ORDER by:

SELECT *
-- FROM (SELECT * FROM treenode ORDER BY parentid, nodeorder)
from treenode
START WITH parentid=0
CONNECT BY PRIOR ID = parentid
order by parentid, nodeorder;

Here are the results:

  SELECT *
  2 -- FROM (SELECT * FROM treenode ORDER BY parentid, nodeorder)   3 from treenode
  4 START WITH parentid=0
  5 CONNECT BY PRIOR ID = parentid
  6* order by parentid, nodeorder
11:24:21 rsysdevdb.radisys.com - jkstill_at_dv01 SQL> /

ID PARENTID NODEORDER DESCRIPTION
---------- ---------- ---------- --------------------

         1          0          0 top folder
         9          1          0 1st subfolder
         2          1          1 2nd subfolder
         4          2          1 folder 2 item 1
         3          2          2 folder 2 item 2
        10          3          1 nested folder2.2.1
        11         10          2 nested folder2.2.2
         6          2          3 folder 2 item 3
         7          1          2 3rd subfolder
         5          7          0 folder 3 item 1
         8          7          1 folder 3 item 2

11 rows selected.

11:24:22 rsysdevdb.radisys.com - jkstill_at_dv01 SQL>

Hey look! The output is working just the way we would like, without the inline view.

Now, remove the commented out line:

SELECT *
from treenode
START WITH parentid=0
CONNECT BY PRIOR ID = parentid
order by parentid, nodeorder;

And the resulting output:

1 SELECT *
  2 from treenode
  3 START WITH parentid=0
  4 CONNECT BY PRIOR ID = parentid
  5* order by parentid, nodeorder
11:25:12 rsysdevdb.radisys.com - jkstill_at_dv01 SQL> /

ID PARENTID NODEORDER DESCRIPTION
---------- ---------- ---------- --------------------

         1          0          0 top folder
         9          1          0 1st subfolder
         2          1          1 2nd subfolder
         7          1          2 3rd subfolder
         4          2          1 folder 2 item 1
         3          2          2 folder 2 item 2
         6          2          3 folder 2 item 3
        10          3          1 nested folder2.2.1
         5          7          0 folder 3 item 1
         8          7          1 folder 3 item 2
        11         10          2 nested folder2.2.2

11 rows selected.

11:25:13 rsysdevdb.radisys.com - jkstill_at_dv01 SQL>

Interesting, no?

Jared

"Madhavan Amruthur" <mad5698_at_fastmail.fm> Sent by: root_at_fatcity.com
11/06/2002 08:23 AM
Please respond to ORACLE-L

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc: 
        Subject:        RE: SQL Brain Teaser Challenge

Hi Steve,
You can get the below query to work in 8.1.7 (not sure about previous versions) by setting the undoc parameter _new_connect_by_enabled = true and can be set for a session

SELECT *
FROM (SELECT * FROM treenode ORDER BY parentid, nodeorder) START WITH parentid=0
CONNECT BY PRIOR ID = parentid

You can also use sys_connect_by_path feature in 9i which gives you the entire hierarchy path (can be used in 8i with the above undoc parameter)

For eg:

select sys_connect_by_path(parent_id,'/') from treenode
start with parent_id = 0
connect by prior id = parent_id

will give you a output like

0/1/9
0/1/2
0/1/2/4

...etc

As always setting an undoc parameter is not advisable unless instructed by Oracle support :-)

Hope this helps.
Regards,

Madhavan
http://www.dpapps.com

--

Madhavan Amruthur
DecisionPoint Applications

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