Query 4 joined tables with internal joins to represent a complex hierarchy!

Question

I've got to refine/replace a query (Oracle 9i) that
currently joins rows from four tables in a hierarchical
fashion that I use to produce a listing like this:
agency abc 1
....division def 1.1
........service ghi 1.1.1
........service jkl 1.1.2
............faq mno 1.1.2.1
............faq pqr 1.1.2.2
........service stu 1.1.3
....division vwx 1.2
........service yyy 1.2.1
............faq zzz 1.2.1.1
The change involves allowing for unlimited levels of
nested child divisions to produce a listing like this:
agency abc 1
....division def 1.1
........service ghi 1.1.1
........service jkl 1.1.2
............faq mno 1.1.2.1
............faq pqr 1.1.2.2
........service stu 1.1.3
....division vwx 1.2
........division xxx 1.2.1
............division aaa 1.2.1.1
............division bbb 1.2.1.2
................service aaa 1.2.1.2.1
....................faq fff 1.2.1.2.1.1
....................faq ggg 1.2.1.2.1.2
........service yyy 1.2.1
............faq zzz 1.2.1.1
Notice the insertion of three nested divisions under
division 1.2 with services and faqs under those. The
order of names throughout is alphabetic within a nesting
level.
Here's the SQL I currently use, without nested divisions
(it contains extra info that I use to control what and
how names are displayed):
SELECT
agency.agency_id AGENCY_ID,
agency.agency_type_id AGENCY_TYPE_ID,
agency.name AGENCY_NAME,
agency.acronym AGENCY_ACRONYM,
agency.expiration_date AGENCY_EXP,
agency.post_count AGENCY_POST,
agency.stat AGENCY_STAT,
agency_type.agency_type AGENCY_TYPE,
division.division_id DIV_ID,
division.name DIV_NAME,
division.transfer_number DIV_TRANS_NUM,
division.expiration_date DIV_EXP,
division.post_count DIV_POST,
division.stat DIV_STAT,
service.service_id SVC_ID,
service.name SVC_NAME,
service.taxonomy SVC_TAX,
service.keywords SVC_KEYWORDS,
service.action_type SVC_ACTION_TYPE,
service.sr_form_name SVC_SR_FORM,
service.expiration_date SVC_EXP,
service.post_count SVC_POST,
service.stat SVC_STAT,
faq.faq_id FAQ_ID,
faq.name FAQ_NAME,
faq.expiration_date FAQ_EXP,
faq.post_count FAQ_POST,
faq.stat FAQ_STAT
FROM
agency,
agency_type,
division left join service on
division.division_id=service.division_id left join
faq on service.service_id=faq.service_id
WHERE (
(agency_type.agency_type_id = agency.agency_type_id)
AND (agency.agency_id = division.agency_id)
AND (agency.agency_id = :agency_id )
It's very fast -- I can retrieve and display 5,000 rows
in seconds using Perl DBI and CGI -- and very easy to use
to produce the hierarchical listing of items from the
four tables. It is also very straightforward since I was
able to generate the SQL using the SQL modeler in TOAD
(I'm not the strongest SQL developer so I resort to
tools).
I need to get jump-started in the right direction to
determine what I need to add to my division table
(div_parent_id?), if I need a div_parent_child table to
define the relationships (rows with parent_id & child_id
pairs), and how to change or rewrite the SQL query. The
CGI form that will be used to define the relationships
will ask users to define children of a given division. I
envision presenting a list of divisions with null
parent_division_id columns for users to select from then
updating selected rows for selected divsions.
Thanks in advance for any help/guidance!
-Gene

Answer 1

INLINE VIEWS!
select whatever_you_want
from (
SELECT FOLDER_ID, PARENT_FOLDER_ID, FOLDER_NAME
FROM FOLDERS
START WITH PARENT_FOLDER_ID = 0 CONNECT BY PARENT_FOLDER_ID = PRIOR FOLDER_ID
) tree, FILES
where tree.folder_id = files.folder_id -- or something like that
always try to keep the CONNECT BY limited to ONE AND ONLY table. then use that query in a subquery, a WITH clause, an inline view or something. do not try to JOIN or UNION with a CONNECT BY. it won't work the way you think it will, and even it returns the expected results, it will perform terribly.
* your mileage may vary
Message was edited by:
shoblock
added exclamation marks to show my excitement!!!!