SUM OVER PARTITION BY condition?

Question

I have a piece of SQL similar to:
SELECT person,
amount,
type,
SUM(amount) OVER (PARTITION BY person) sum_amount_person
FROM table_a
What I would like to be able to do is use a conditional PARTITION BY clause, so rather than partition and summing for each person I would like to be able to sum for each person where type = 'ABC'
I would expect the syntax to be something like
SELECT person,
amount,
type,
SUM(amount) OVER (PARTITION BY person WHERE type = 'ABC') sum_amount_person
FROM table_a
Is this possible? Or am I missing a much simpler solution?
Richard

Answer 1

The proposed query does not compile on my Windows Oracle 9.2.0.5 or 10.1. This could be generated by the ambiguty introduced by DECODE in the evaluation of query (does it filter the selected rows, or the rows summarized for each selected row, or both?).
I propose two alternatives. The requirements are not specific enough to allow me to choose between them.
SQL> SELECT * FROM table_a ORDER BY 1, 3;
PERSON         AMOUNT TYP
john               12 abc
john                8 abc
john               20 def
mike               15 abc
mike               30 ghi
steve              30 abc
6 rows selected.
SQL> SELECT person,
  2  amount,
  3  type,
  4  SUM(decode(type, 'ABC',amount, to_number(NULL)) OVER (PARTITION BY person) sum_amount_person
  5  FROM table_a;
SUM(decode(type, 'ABC',amount, to_number(NULL)) OVER (PARTITION BY person) sum_amount_person
ERROR at line 4:
ORA-30483: window  functions are not allowed here
SQL> SELECT person,
  2  amount,
  3  type,
  4  CASE type WHEN 'abc' THEN SUM(amount) OVER (PARTITION BY person) END sum_amount_person
  5  FROM table_a;
PERSON         AMOUNT TYP SUM_AMOUNT_PERSON
john               12 abc                40
john               20 def
john                8 abc                40
mike               15 abc                45
mike               30 ghi
steve              30 abc                30
6 rows selected.
SQL> SELECT person,
  2  amount,
  3  type,
  4  CASE type WHEN 'abc' THEN SUM(amount) OVER (PARTITION BY person, type) END sum_amount_person
  5  FROM table_a;
PERSON         AMOUNT TYP SUM_AMOUNT_PERSON
john               12 abc                20
john                8 abc                20
john               20 def
mike               15 abc                15
mike               30 ghi
steve              30 abc                30
6 rows selected.