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sqloraclesumwindow-functions

Oracle SQL: Update Table with SUM OVER PARTITION

I've been trying to do the following:

CREATE TABLE T_example
(category number(1,0),
amount number(4,0),
amount2 number(4,0))

INSERT INTO T_example VALUES (1,20,40);
INSERT INTO T_example VALUES (1,30,40);
INSERT INTO T_example VALUES (2,5,60);
INSERT INTO T_example VALUES (2,15,60);
INSERT INTO T_example VALUES (2,30,60);

As you can see all rows contain the same amount2 within their category. Now i want to spread amount2 within each category according to the distribution of amount with the category.

UPDATE T_example
SET amount2 = amount2 * amount / SUM(amount) OVER (PARTITION BY category ORDER BY category);

I want to get:

category - amount - amount2
1 - 20 - 16
1 - 30 - 24
2 - 5 - 6
2 - 15 - 18
2 - 30 - 36

But the code doesn't work. It says:

00934.00000 - "group function is not allowed here"

Can you tell me where I am mistaken?

Solution

  • I think below will work for you,co-related sub-query

     UPDATE T_example t1
    SET t1.amount2 = (t1.amount*t1.amount2) / (

       select sum(amount) from -- from was missing
      T_example t2 where t2.category=t1.category
      group by category

            );

    https://dbfiddle.uk/?rdbms=oracle_11.2&fiddle=e2c00fe7ad8866bb4a62f66b08133f95

    CATEGORY    AMOUNT  AMOUNT2
1            20     16
1            30     24
2             5     6
2            15     18
2            30     36