CONNECT BY to get uppermost node

Question

Hello all,
I'm hoping someone can help me, or point me in the right direction
I need to create a query for an lov.
The query contains all open work orders with a category of 'WTPR'. The work orders are hierarchical, so I only want the uppermost parent.
I know I require a CONNECT BY statement of some kind, but I'm just not seeing it.
I also need to pull everything, so I don't know what I could use for the 'START WITH' clause.
Sample Data:
CO#______Parent CO_____Category
CO51399________________WTRS
CO51401__CO51399______WTPR
CO51398__CO51401______WTRS
CO51397__CO51398______WTPR
CO51400__CO51397______WTRS
Result:
Pull CO51401 from this hierarchy. (Uppermost parent w/category WTPR)
I have this so far...but I have no idea how to consistently distinguish the highest node returned...
select co.co
, co.PARENT
, co.category
, level X
from usd_CHANGEORDERS co
where co.status = 'OP'
and co.category = 'WTPROJ'
CONNECT BY prior CO = parent
Thanks,
Janel

Answer 1

CONNECT_BY_ROOT is only part of the solution but won't work as the solution because the OP want's the minimum parent node that has a particular value for category. In the sample data the parent C051399 has the wrong category. What you need to do is select the record with the minimum level that meets your criteria.
To do that you need to add a starts with clause to your current select so that you alway root your heirarchy on a node with no parent, then you need to determin the minimum level for any given root node that meets your criteria:
with usd_CHANGEORDERS as (select 'CO51399' CO,
      cast(null as varchar2(7)) parent,
      'WTRS' Category, 'OP' status from dual
  union all select 'CO51401', 'CO51399', 'WTPR', 'OP' from dual
  union all select 'CO51398', 'CO51401', 'WTRS', 'OP' from dual
  union all select 'CO51397', 'CO51398', 'WTPR', 'OP' from dual
  union all select 'CO51400', 'CO51397', 'WTRS', 'OP' from dual
), heirarchy as (
  select connect_by_root co.co cop
      , co.co
      , co.PARENT
      , co.category
      , level X
  from usd_CHANGEORDERS co
  where co.status = 'OP'
  and co.category = 'WTPR'
  CONNECT BY prior CO = parent
  start with parent is null
), getminx as (
  select h.*
       , min(x) over (partition by cop) minx
  from heirarchy h
select * from getminx
where x = minx;
COP     CO      PARENT  CATEGORY X                      MINX                  
CO51399 CO51401 CO51399 WTPR     2                      2                     
1 rows selectedMessage was edited by:
Sentinel