Help needed with Connect By clause

Question

Hi all,
i have following hierarchical structure,
          a     
         0  |    0
            |b
     0  / \   1
         d/   \c                 
         0 \ /   1                
            |e
      0  |    0
            |f
      0  |    0
         |g
"a" is start item
"g" is end item
i have 2 branches as shown above
branch 1 - a --> b --> d --> e --> f --> g
              0     0    0     0     0   
branch 2 - a --> b --> c --> e --> f --> g
           0     1     1    0     0
Branch 1 is my Main branch
Branch 2 is my alternate branch  with common start and end item,
when i use the following query i get ouptut of branch 1
Select t.p_ml,
       t.s_ml,
       t.flag,
        Level          lev
FROM    test t
CONNECT BY Prior s_ml = p_ml
And flag = 0
START WITH p_ml = 'g'
And flag = 0
        P_ML     S_ML     FLAG     LEV
1     g     f     0     1
2     f     e     0     2
3     e     d     0     3
4     d     b     0     4
5     b     a     0     5
what i need is output of branch 2 as shown below
P_ml  S_ml  flag
g     f     0             -->end item
f     e     0
e     c     1
c     b     1
b     a     0             --> start item;
The table strcutre and data is given below,
create table TEST
  P_ML VARCHAR2(4),
  S_ML VARCHAR2(4),
  FLAG NUMBER(2)
insert into TEST (P_ML, S_ML, FLAG)
values ('f', 'e', 0);
insert into TEST (P_ML, S_ML, FLAG)
values ('e', 'd', 0);
insert into TEST (P_ML, S_ML, FLAG)
values ('d', 'b', 0);
insert into TEST (P_ML, S_ML, FLAG)
values ('b', 'a', 0);
insert into TEST (P_ML, S_ML, FLAG)
values ('g', 'f', 0);
insert into TEST (P_ML, S_ML, FLAG)
values ('e', 'c', 1);
insert into TEST (P_ML, S_ML, FLAG)
values ('c', 'b', 1);  
kindly assist me, if anything not clear let me know,regards
nic
Message was edited by:
Nicloei W
Message was edited by:
Nicloei W

Answer 1

Well i've modified my solution, Now it will perform for both the same number of nodes in two branch and as well as different number of nodes in two branch. Hope this will work for you.
First case,
Same number of nodes in both the branch-
satyaki>
satyaki>drop table test;
Table dropped.
Elapsed: 00:00:10.46
satyaki>
satyaki>
satyaki>create table TEST
  2  (
  3    P_ML VARCHAR2(4),
  4    S_ML VARCHAR2(4),
  5    FLAG NUMBER(2)
  6  );
Table created.
Elapsed: 00:00:00.73
satyaki>
satyaki>
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('f', 'e', 0);
1 row created.
Elapsed: 00:00:00.23
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('e', 'd', 0);
1 row created.
Elapsed: 00:00:00.01
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('d', 'b', 0);
1 row created.
Elapsed: 00:00:00.01
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('b', 'a', 0);
1 row created.
Elapsed: 00:00:00.00
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('g', 'f', 0);
1 row created.
Elapsed: 00:00:00.03
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('e', 'c', 1);
1 row created.
Elapsed: 00:00:00.04
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('c', 'b', 1);
1 row created.
Elapsed: 00:00:00.03
satyaki>
satyaki>
satyaki>commit;
Commit complete.
Elapsed: 00:00:00.07
satyaki>
satyaki>
satyaki>
satyaki>
satyaki>
satyaki>with t
  2  as
  3    (
  4      select distinct p_ml,
  5             s_ml,
  6             flag,
  7             lev
  8      from (
  9              select p_ml,
10                     s_ml,
11                     flag,
12                     row_number() over(partition by lev order by p_ml,s_ml,flag ) rn,
13                     row_number() over(partition by lev order by p_ml desc,s_ml desc,flag desc) r
n_alt,
14                     lev
15             from (
16                     Select t.p_ml,
17                            t.s_ml,
18                            t.flag,
19                            Level          lev
20                     FROM    test t
21                     CONNECT BY Prior s_ml = p_ml
22                     START WITH p_ml = 'g'
23                     --And flag = 0
24                  )
25           )
26     where rn = 1
27     --where rn_alt=1
28     order by lev desc
29    ),
30  sat as
31   (
32     select a.s_ml||' -> '||a.p_ml  graph_disp,
33            a.lev
34     from t a
35     CONNECT BY Prior a.s_ml = a.p_ml
36     START WITH a.p_ml = 'g'
37   ),
38  satyaki as
39   (
40     select graph_disp,lev,
41            row_number() over(partition by graph_disp order by lev desc) rn
42     from sat
43   )
44  select graph_disp
45  from satyaki
46  where rn = 1
47  order by lev desc;
GRAPH_DISP
a -> b
b -> c
c -> e
e -> f
f -> g
Elapsed: 00:00:00.59
satyaki>
satyaki>
satyaki>
satyaki>ed
Wrote file afiedt.buf
  1  with t
  2  as
  3    (
  4      select distinct p_ml,
  5             s_ml,
  6             flag,
  7             lev
  8      from (
  9              select p_ml,
10                     s_ml,
11                     flag,
12                     row_number() over(partition by lev order by p_ml,s_ml,flag ) rn,
13                     row_number() over(partition by lev order by p_ml desc,s_ml desc,flag desc) rn_alt,
14                     lev
15             from (
16                     Select t.p_ml,
17                            t.s_ml,
18                            t.flag,
19                            Level          lev
20                     FROM    test t
21                     CONNECT BY Prior s_ml = p_ml
22                     START WITH p_ml = 'g'
23                     --And flag = 0
24                  )
25           )
26     --where rn = 1
27     where rn_alt=1
28     order by lev desc
29    ),
30  sat as
31   (
32     select a.s_ml||' -> '||a.p_ml  graph_disp,
33            a.lev
34     from t a
35     CONNECT BY Prior a.s_ml = a.p_ml
36     START WITH a.p_ml = 'g'
37   ),
38  satyaki as
39   (
40     select graph_disp,lev,
41            row_number() over(partition by graph_disp order by lev desc) rn
42     from sat
43   )
44  select graph_disp
45  from satyaki
46  where rn = 1
47* order by lev desc
satyaki>/
GRAPH_DISP
a -> b
b -> d
d -> e
e -> f
f -> g
Elapsed: 00:00:01.03
satyaki>
satyaki>Second case,
Different number of nodes in both the branch-
satyaki>
satyaki>
satyaki>drop table test;
Table dropped.
Elapsed: 00:00:03.92
satyaki>
satyaki>
satyaki>
satyaki>create table TEST
  2   (
  3      P_ML VARCHAR2(4),
  4      S_ML VARCHAR2(4),
  5      FLAG NUMBER(2)
  6   );
Table created.
Elapsed: 00:00:00.62
satyaki>
satyaki>
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('f', 'e', 0);
1 row created.
Elapsed: 00:00:00.18
satyaki>
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('e', 'x', 0);
1 row created.
Elapsed: 00:00:00.03
satyaki>
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('x', 'd', 0);
1 row created.
Elapsed: 00:00:00.04
satyaki>
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('d', 'b', 0);
1 row created.
Elapsed: 00:00:00.03
satyaki>
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('b', 'a', 0);
1 row created.
Elapsed: 00:00:00.03
satyaki>
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('g', 'f', 0);
1 row created.
Elapsed: 00:00:00.02
satyaki>
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('e', 'c', 1);
1 row created.
Elapsed: 00:00:00.11
satyaki>
satyaki>insert into TEST (P_ML, S_ML, FLAG)
  2  values ('c', 'b', 1);
1 row created.
Elapsed: 00:00:00.05
satyaki>commit;
Commit complete.
Elapsed: 00:00:00.07
satyaki>
satyaki>
satyaki>with t
  2  as
  3    (
  4      select distinct p_ml,
  5             s_ml,
  6             flag,
  7             lev
  8      from (
  9              select p_ml,
10                     s_ml,
11                     flag,
12                     row_number() over(partition by lev order by p_ml,s_ml,flag ) rn,
13                     row_number() over(partition by lev order by p_ml desc,s_ml desc,flag desc) r
n_alt,
14                     lev
15             from (
16                     Select t.p_ml,
17                            t.s_ml,
18                            t.flag,
19                            Level          lev
20                     FROM    test t
21                     CONNECT BY Prior s_ml = p_ml
22                     START WITH p_ml = 'g'
23                     --And flag = 0
24                  )
25           )
26     where rn = 1
27     --where rn_alt=1
28     order by lev desc
29    ),
30  sat as
31   (
32     select a.s_ml||' -> '||a.p_ml  graph_disp,
33            a.lev
34     from t a
35     CONNECT BY Prior a.s_ml = a.p_ml
36     START WITH a.p_ml = 'g'
37   ),
38  satyaki as
39   (
40     select graph_disp,lev,
41            row_number() over(partition by graph_disp order by lev desc) rn
42     from sat
43   )
44  select graph_disp
45  from satyaki
46  where rn = 1
47  order by lev desc;
GRAPH_DISP
a -> b
b -> c
c -> e
e -> f
f -> g
Elapsed: 00:00:00.34
satyaki>
satyaki>
satyaki>ed
Wrote file afiedt.buf
  1  with t
  2  as
  3    (
  4      select distinct p_ml,
  5             s_ml,
  6             flag,
  7             lev
  8      from (
  9              select p_ml,
10                     s_ml,
11                     flag,
12                     row_number() over(partition by lev order by p_ml,s_ml,flag ) rn,
13                     row_number() over(partition by lev order by p_ml desc,s_ml desc,flag desc) rn_alt,
14                     lev
15             from (
16                     Select t.p_ml,
17                            t.s_ml,
18                            t.flag,
19                            Level          lev
20                     FROM    test t
21                     CONNECT BY Prior s_ml = p_ml
22                     START WITH p_ml = 'g'
23                     --And flag = 0
24                  )
25           )
26     --where rn = 1
27     where rn_alt=1
28     order by lev desc
29    ),
30  sat as
31   (
32     select a.s_ml||' -> '||a.p_ml  graph_disp,
33            a.lev
34     from t a
35     CONNECT BY Prior a.s_ml = a.p_ml
36     START WITH a.p_ml = 'g'
37   ),
38  satyaki as
39   (
40     select graph_disp,lev,
41            row_number() over(partition by graph_disp order by lev desc) rn
42     from sat
43   )
44  select graph_disp
45  from satyaki
46  where rn = 1
47* order by lev desc
satyaki>/
GRAPH_DISP
a -> b
b -> d
d -> x
x -> e
e -> f
f -> g
6 rows selected.
Elapsed: 00:00:00.48
satyaki>Regards.
Satyaki De.
N.B.: Total i've posted 4 SELECT queries. In both the case, First query denotes the details of 1st branch and the 2nd query denotes another branch. Hope this will work for you. :)