Bill of Materials style query ( hierarchical query question)

Question

Hi,
I'm having difficulty trying to SQL query for the following.
*(1) Outline of proposed table design*
SERVERS
SERVER_ID
SERVER_DESC
etc.
SERVER-MAJORCOMPONENTS
SERVER_ID
COMPONENT_ID
SERVER-PARTS
COMPONENTS_ID
PARENT_COMPONENT_ID
COMPONENT_DESC
etc.
*(2) Text Description*
-- Server A is made up of components P1,P2 and S2.
-- P1 and P2 are major components and would therefore feature in SERVER-MAJORCOMPONENTS that lists all major components (P1,P2,P3 .....P256 etc.) that make up the server.
-- S2 is a minor component and therefore would not be listed in SERVER-MAJORCOMPONENTS, however it would be listed as a child component of component P2 in SERVER-PARTS.
-- A manufacturer issues a safety recall on part S2, based upon an input of a SERVER_ID, I need to know whether that server contains part S2.
Query input : SERVER_ID
Query output : (a) "no rows selected" if server does not contain component (b) count=1,component_id or whatever ... single row
*(3) ASCII ART*
----------> P1
SERVER A
----------> P2
x-------> S1
x--------> S2
Thank you in advance !

Answer 1

Hierarhical structures Oracle can easily deal with are (using graph theory terminology) trees.
(defined as: all members except one - the root - have a single parent)
It seems you call the roots "groups" and all other elements "roles"
I find Sanjay's example perfectly suitable.
To describe the structure role and parent_role can do the job.
Suppose you have a table role_hierarchy containing data like:
====================
role | parent_role |
====================
   1 |             | group
   2 |           1 | role
   3 |           1 | role
   3 |          10 | role
   3 |          11 | role
   4 |           2 | role
   4 |           3 | role
   5 |           2 | role
   5 |           3 | role
   5 |          10 | role
   6 |           2 | role
   6 |          10 | role
   7 |           6 | role
   8 |           7 | role
   8 |          11 | role
   9 |           7 | role
   9 |          11 | role
  10 |             | group
  11 |             | group
This data represents three trees:
    1              10              11
   / \            /| \            / |\
  2   3          3 5  6          3  8 9
/|\  |\        /|    |         / \
4 5 6 4 5      4 5    7        4   5
    |                / \
    7               8   9
  8   9
If I understand correctly:
- every table row is owned by some (single) group
- a user is assigned some (single) role suppose 7
I don't have database access and have some connection problems right now so I can just describe it:
Using sys_connect_by_path function in Sanjay's example you'll be able to obtain two paths:
7-6-2-1 from the first and 7-6-10 from the second group
after constructing the string -1-10- containing the valid groups the user can access rows where
INSTR('-1-10-','-'||to_char(group_of_row)||'-') > 0Regards
Etbin