Pivot help on an heirarchy query

Question

I've looked through the FAQs but I'm just not seeing it.
I have the following:
A query returning:
o_id   oname            typ  prnt
118    Pension Admin    PRC    91
91     Retirement       LOB   218
218    Benefits         SEG    81
119    Plan Mgmt        PRC    91
91     Retirement       LOB   218
218    Benefits         SEG    81
142    RCS Software     PRC    93
93     Risk Software    LOB   221
221    Risk Services    SEG    81I want the following:
ID  PRC              LOB               SEG
118 Pension Admin    Retirement        Benefits
119 Plan Mgmt        Retirement        Benefits
142 RCS Software     Risk Software     Risk ServicesVersion:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE 11.2.0.1.0 Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production
Sample data:
create table t1( o_id  number(3)
               , oname varchar2(20)
               , typ  varchar2(3)
               , prnt number(3)
insert into t1 values(118,   'Pension Admin',  'PRC',  91);
insert into t1 values(91,    'Retirement',     'LOB', 218);
insert into t1 values(218,   'Benefits',       'SEG',  81);
insert into t1 values(119,   'Plan Mgmt',      'PRC',  91);
insert into t1 values(142,   'RCS Software',   'PRC',  93);
insert into t1 values(93,    'Risk Software',  'LOB', 221);
insert into t1 values(221,   'Risk Services',  'SEG',  81);I can't get past:
select level lvl, org.*
  from t1 org
  start with typ = 'PRC'
  connect by  o_id =  prior prnt;I've tried this, but of course it returns only one row:
select *
  from (
         select lvl, oname
           from ( 
                  select level lvl, t1.*
                    from t1
                   start with typ = 'PRC'
                 connect by  o_id =  prior prnt
pivot ( min(oname)  for lvl in (1  prc, 2 lob, 3 seg) )What am I missing, any help would be appreciated.

Answer 1

Hi,
Thanks for posting the CREATE TABLE and INSERT statements; that's very helpful!
Use CONNECT_BY_ROOT to remember the starting point that led to each row of output, which is what identifies which row of output each row of the CONNECT BY results corresponds to.
Sorry, I'm not at an Oracle 11 system now. This works in Oracle 10 (and up):
WITH     connect_by_results     AS
     SELECT     LEVEL               AS lvl
     ,      oname
       ,     CONNECT_BY_ROOT     o_id     AS starting_o_id
     FROM     t1
       START WITH     typ      = 'PRC'
     CONNECT BY     o_id      =  PRIOR prnt
SELECT       starting_o_id
,       MIN (CASE WHEN lvl = 1 THEN oname END)     AS prc
,       MIN (CASE WHEN lvl = 2 THEN oname END)     AS lob
,       MIN (CASE WHEN lvl = 3 THEN oname END)     AS seg
FROM       connect_by_results
GROUP BY  starting_o_id
ORDER BY  starting_o_id
;You can adapt the main query to use SELECT ... PIVOT.
Do you really need separate columns for the different levels? If not, you could do something like this:
SELECT     CONNECT_BY_ROOT     o_id     AS starting_o_id
,      REPLACE ( SYS_CONNECT_BY_PATH ( RPAD (oname, 15)
                          , '`'
          , '`'
          )     AS prc_lob_seg
FROM     t1
WHERE     CONNECT_BY_ISLEAF     = 1
START WITH     typ      = 'PRC'
CONNECT BY     o_id      =  PRIOR prnt
ORDER BY     starting_o_id
;Ouptut:
STARTING_O_ID PRC_LOB_SEG
          118 Pension Admin  Retirement     Benefits
          119 Plan Mgmt      Retirement     Benefits
          142 RCS Software   Risk Software  Risk ServicesNot only is this simpler, it works for any number of levels.
Edited by: Frank Kulash on Jan 16, 2012 4:25 PM
Added SYS_CONNECT_BY_PATH alternative.