Question

I need to use a where clause within an over clause. How?

SELECT SUM(amount) OVER(WHERE dateval > 12)

Or something like that.

–EDIT–

More details

My table is formatted with a year, month, and amount column.

I want to select all the year, month, and amount rows AND create a fourth ‘virtual column’ that has the sum of the past 12 months of amount column.

For example:

YEAR | MONTH | AMOUNT
2001 | 03 | 10
2001 | 05 | 25
2001 | 07 | 10

Should create:

YEAR | MONTH | AMOUNT | ROLLING 12 MONTHS
2001 | 03 | 10 | 10
2001 | 05 | 25 | 35
2001 | 07 | 10 | 45

Answer 1

Given a query against your three-column resultset, does the below work for you?

SELECT
    SUM(amount) OVER(ORDER BY YEAR ASC, MONTH ASC
                     ROWS BETWEEN 11 PRECEDING AND CURRENT ROW)
...