Nodes in the tree

Question

Hi,
Database: ORacle 11g
Query1:
SELECT rank() OVER (PARTITION BY mgr ORDER BY empno) r,
      empno, ename,mgr FROM emp
      start with mgr=7839
      connect by prior empno = mgr
Result set:
r  empno  ename mgr
1
7788
SCOTT
7566
2
7902
FORD
7566
1
7499
ALLEN
7698
2
7521
WARD
7698
3
7654
MARTIN
7698
4
7844
TURNER
7698
5
7900
JAMES
7698
1
7934
MILLER
7782
1
7876
ADAMS
7788
1
7566
JONES
7839
2
7698
BLAKE
7839
3
7782
CLARK
7839
1
7369
SMITH
7902
Query2:
SELECT LTRIM(SYS_CONNECT_BY_PATH(r, '.'), '.') node ,
    LPAD (' ', 2 * (LEVEL - 1))   ||  mgr , struc.* 
    FROM
      SELECT rank() OVER (PARTITION BY mgr ORDER BY empno) r,
      empno, ename,mgr FROM emp
      start with mgr=7839
      connect by prior empno = mgr
) struc
start with mgr=7839
connect by prior empno = mgr
Result set:
node  mgr      r   empno  ename mgr
1
7839
1
7566
JONES
7839
1.1
  7566
1
7788
SCOTT
7566
1.1.1
    7788
1
7876
ADAMS
7788
1.2
  7566
2
7902
FORD
7566
1.2.1
    7902
1
7369
SMITH
7902
2
7839
2
7698
BLAKE
7839
2.1
  7698
1
7499
ALLEN
7698
2.2
  7698
2
7521
WARD
7698
2.3
  7698
3
7654
MARTIN
7698
2.4
  7698
4
7844
TURNER
7698
2.5
  7698
5
7900
JAMES
7698
3
7839
3
7782
CLARK
7839
3.1
  7782
1
7934
MILLER
7782
Is this representation of node column is correct?
Can anyone pplease explain to me step by step how the above query2 executes
Thanks

Answer 1

Hi,
GopalaKrishna wrote:
Hi Frank,
Actually I thought there might be some standard representation of node structure in hierarchical tree.That's why I have asked is that representation of node structure correct or not?
Sorry I am newbie in this concepts.
I was expecting the below type of result set but it turned out  as above result set in original request.More over I did nt understand sys_connect_by_path at that time I will get back to you once I understand  the previous request of mine where you explained it nicely...
1
7839
1.1
  7566
1.1.1
    7788
1.1.1.1
     7876
1.1.2
    7902
1.1.2.1
      7369
1.2
  7698
1.2.1
   7900
1.2.2
   7521
1.2.3
   7499
1.2.4
   7654
1.2.5
   7844
1.3
  7782
1.3.1
   7934
Sometimes people attach numbers to the tree like you did, but most of the time they don't find it necessary.
So, you were expecting to see 14 rows of output, starting with the node that represents 'KING'.  Instead, you got 13 rows, starting with the people who report directly to 'KING'.  If you want to start with 'KING', then change the START WITH clause to start with 'KING':
WITH got_child_num  AS
    SELECT empno, mgr, ename
    ,      ROW_NUMBER () OVER ( PARTITION BY  mgr
                                ORDER BY      empno
                              )   AS child_num
    FROM    scott.emp
SELECT  SUBSTR ( SYS_CONNECT_BY_PATH (child_num, '.')
               , 2
               )               AS node
,       LPAD ( ' '
             , 2 * (LEVEL - 1)
             ) || empno        AS iempno
,       empno, ename, mgr
FROM    got_child_num
START WITH  mgr   IS NULL
CONNECT BY  mgr   = PRIOR empno
Output:
NODE       IEMPNO               EMPNO ENAME             MGR
1          7839                  7839 KING
1.1          7566                7566 JONES            7839
1.1.1          7788              7788 SCOTT            7566
1.1.1.1          7876            7876 ADAMS            7788
1.1.2          7902              7902 FORD             7566
1.1.2.1          7369            7369 SMITH            7902
1.2          7698                7698 BLAKE            7839
1.2.1          7499              7499 ALLEN            7698
1.2.2          7521              7521 WARD             7698
1.2.3          7654              7654 MARTIN           7698
1.2.4          7844              7844 TURNER           7698
1.2.5          7900              7900 JAMES            7698
1.3          7782                7782 CLARK            7839
1.3.1          7934              7934 MILLER           7782
I find it rather neat how the first 2 columns stay a fixed difference apart in this output.  As the node column gets bigger or smaller, there is correspondingly more or less padding in the iempno column.