Circular Dependency in data

Question

Im usiing oracle 9i.
I have the following table
create table JOB_DEPENDS
JOB VARCHAR2(40) not null,
SUBJOB VARCHAR2(40) not null,
DEP_JOB VARCHAR2(40) not null,
DEP_SUBJOB VARCHAR2(40) not null
sample data:-
insert into JOB_DEPENDS (JOB, SUBJOB, DEP_JOB, DEP_SUBJOB)
values ('A', 'SA', 'B', 'SB');
insert into JOB_DEPENDS (JOB, SUBJOB, DEP_JOB, DEP_SUBJOB)
values ('B', 'SB', 'C', 'SC');
insert into JOB_DEPENDS (JOB, SUBJOB, DEP_JOB, DEP_SUBJOB)
values ('C', 'SC', 'A', 'SA');
insert into JOB_DEPENDS (JOB, SUBJOB, DEP_JOB, DEP_SUBJOB)
values ('D', 'SD', 'E', 'SE');
Commit;
Based on he above data
Job A depends on job B to run.
Job B depends on job C to run.
Job C depends on job A to run.
Thus there is circular dependency between the data A->B->C->A.
I need a sql query to identify the circular dependent data.
Output of the sql query should be like below
JOB     SUBJOB     DEP_JOB     DEP_SUBJOB
A     SA     B     SB
B     SB     C     SC
C     SC     A     SA
In the above example circular dependency is between 3 jobs.
I need an sql which finds circular dependency between any number of jobs
Thanks in advance

Answer 1

Hi,
Sorry but I was traveling this afternoon and I could not reply immediately.
You did not explain in the first post that the relation is with job AND subjob with dep_job and dep_subjob.
Based on he above data
Job A depends on job B to run.
Job B depends on job C to run.
Job C depends on job A to run.Sorry but my crystal ball has broken for longtime :-)
Anyway I have 2 assumptions that you have to confirm:
a) No duplicate records (same job, subjob, dep_job, dep_subjob)
b) Hierarchical relation among records is job=dep_job AND subjob=dep_subjob
If these assumptions are correct here below is the modifed script:
SET SERVEROUTPUT ON SIZE UNLIMITED
DECLARE
   e_infinite_loop  EXCEPTION;
   PRAGMA EXCEPTION_INIT (e_infinite_loop, -01436);
   l_count          INTEGER;
BEGIN
   FOR c1 IN (SELECT job, subjob, dep_job, dep_subjob FROM job_depends)
   LOOP
      BEGIN
         SELECT COUNT(*)
           INTO l_count
           FROM job_depends j
          START WITH job = c1.job AND subjob=c1.subjob
                 AND dep_job=c1.dep_job AND dep_subjob=c1.dep_subjob
        CONNECT  BY job = PRIOR dep_job AND subjob = PRIOR dep_subjob;
      EXCEPTION
         WHEN e_infinite_loop
         THEN
            DBMS_OUTPUT.PUT_LINE('Infinite loop detected on Job: '|| c1.job ||' '|| c1.subjob ||' '|| c1.dep_job ||' '|| c1.dep_subjob);
      END;
   END LOOP;
END;
and the output is:
Infinite loop detected on Job: A SA B SB
Infinite loop detected on Job: B SB C SC
Infinite loop detected on Job: C SC1 A SA
Infinite loop detected on Job: C SC C SC1
{code}
Regards
Al