Finding missing components between two tables

Question

If I had a table named package_part which has several columns:
Site
Parent
Sequence
Child
Qty_per_assembly
Contents eg:
WH1, 123, 1, A, 1
WH1, 123, 2, B, 2
WH1, 123, 3, C, 1
WH2, 123, 1, A, 1
WH2, 123, 2, C, 1
WH2, 123, 3, E, 3
I want to report packages which have missing components between either site.
WH1, 123, 2, B, 2 is missing from site WH2
WH2, 123, 3, E, 3 is missing from site WH1
I just cannot figure it out!
Thanks

Answer 1

Depending on your version you could use analytic functions:
WITH package_part AS (SELECT 'WH1' site, 123 parent, 1 SEQUENCE, 'A' CHILD, 1 qty_per_assembly
                        FROM dual
                       UNION
                      SELECT 'WH1', 123, 2, 'B', 2
                        FROM dual
                       UNION
                      SELECT 'WH1', 123, 3, 'C', 1
                        FROM dual
                       UNION
                      SELECT 'WH2', 123, 1, 'A', 1
                        FROM dual
                       UNION
                      SELECT 'WH2', 123, 2, 'C', 1
                        FROM dual
                       UNION
                      SELECT 'WH2', 123, 3, 'E', 3
                        FROM dual
SELECT site, parent, SEQUENCE, CHILD, qty_per_assembly
  FROM (SELECT pp.*, COUNT(*) OVER (PARTITION BY parent, CHILD, qty_per_assembly) no_entries 
          FROM package_part pp
WHERE no_entries < 2
;There's also a nice article in Oracle Magazine on this topic.
C.