Join two Connect By Prior Start With trees and return only common records?

Question

Oracle 10g Release 2 (10.2)
I have two tables that have tree structured data. The results, when running the queries individually are correct, however I need to join tree one to tree two in order to obtain only the common records between them.
-- Tree one
SELECT ip_entity_name, entity_code, hier_level, entity_parent
FROM ip_hierarchy
WHERE hier_level >= 3
CONNECT BY PRIOR entity_code = entity_parent
START WITH entity_code = 'MEWWD';
-- Tree two
SELECT ip_entity_name, entity_code, hier_level, entity_parent
FROM ipt_hierarchy
WHERE hier_level >= 3
CONNECT BY PRIOR entity_code = entity_parent
START WITH entity_code = 'IPNAM';
As I understand, joins may not work with CONNECT BY/START WITH queries?
Is a WITH clause an option?
If at all possible, I don't want to put one select in a View database object and join against the other query.
Thanks.

Answer 1

Hi JTP51,
You can use WITH clause or sub-query by using in-line view, without creating any view object in database.
for example
SELECT A.IP_ENTITY_NAME, A.ENTITY_CODE, ....
  FROM (SELECT IP_ENTITY_NAME, ENTITY_CODE, HIER_LEVEL, ENTITY_PARENT
          FROM IP_HIERARCHY
         WHERE HIER_LEVEL >= 3
        CONNECT BY PRIOR ENTITY_CODE = ENTITY_PARENT
         START WITH ENTITY_CODE = 'MEWWD') A,
       (SELECT IP_ENTITY_NAME, ENTITY_CODE, HIER_LEVEL, ENTITY_PARENT
          FROM IPT_HIERARCHY
         WHERE HIER_LEVEL >= 3
        CONNECT BY PRIOR ENTITY_CODE = ENTITY_PARENT
         START WITH ENTITY_CODE = 'IPNAM') B
WHERE A. ENTITY_CODE = B. ENTITY_CODE
AND ....Best regards,
Zhxiang
Edited by: zhxiangxie on Feb 2, 2010 5:35 PM