SQL: Store Calculated value of column and use it for further manipulation

Question

I Have a Table with Id , Gross Amount and Amount Applied .

ID | Gross Amt | Amt Applied | Outstanding Amount
1  |   100     |    10       |    90
1  |   100     |    10       |    80
1  |   100     |    10       |    70

How to get outstanding Amount value for each column for same id.

Thanks

Answer 1

If I understand correctly, you can use a cumulative sum. However, that depends on the ordering of the rows. SQL tables represent unordered sets. You need a column to specify the ordering.

Assuming you have such a column, you can use the ANSI-standard function for cumulative sums in most databases:

select t.*,
       (gross_amount - sum(amt_applied) over (partition by id order by ?)
       ) as outstanding_amount
from t;

The ? is for the ordering column.