Thanks for the question regarding "connect by ", versi

December 9, 2003 - 2am Central time zone Bookmark | Bottom | Top
Reviewer: umesh from blore
SQL> l
1 SELECT
2 DECODE ( ll ,1 , crit1.name ) one ,
3 DECODE ( ll ,2 , crit1.name) two ,
4 DECODE ( ll ,3 , crit1.name) three ,
5 DECODE ( ll ,4 , crit1.name) four
6 FROM
7 (SELECT sc_id_child , sc_id_parent , LEVEL ll FROM CNT_SEARCH_HIERARCHY src
8 START WITH sc_id_parent='crite000000000000002'
9 CONNECT BY PRIOR sc_id_child=sc_id_parent
10 ) , CNT_SEARCH_CRITERIA crit , CNT_SEARCH_CRITERIA crit1
11 WHERE crit.id = sc_id_parent
12* AND crit1.id=sc_id_child
SQL> /
ONE TWO THREE FOUR
-------------------------- --------------------------- ------------------------
-------------------
Building Automation
ACSELON
Authorized Trainer
Programs
Delivery & Installation
ADEPT
Project
Management
Human Resources
Love it, but ... March 4, 2004 - 3pm Central time zone Bookmark | Bottom | Top
Reviewer: Peter Tran from Houston, TX USA
Hi Tom,
What happens if you have a dataset where the top mgr refers to himself? Using your example, if the
MGR = 7839 for KING and I run the same query you have Oracle gives me a:
ORA-01436: CONNECT BY loop in user data
A connect by record cannot reference itself otherwise we have an infinite loop situation.
Is there anyway I can filter this out? In other words, I still want the answer you got earlier,
but now I have the situation where KING refers to himself in the MGR column.
Thanks,
-Peter
Followup March 4, 2004 - 3pm Central time zone:
that case is easy -- since we have the "loop" in a single row, we can simply filter it out in the
"connect by" clause:
ops$tkyte@ORA9IR2> create table emp as select * from scott.emp;
Table created.
ops$tkyte@ORA9IR2> update emp set mgr = empno where mgr is null;
1 row updated.
ops$tkyte@ORA9IR2> commit;
Commit complete.