SQL Server 2014 sum based on previous record

Question

I have the following 3 columns. Col3 first value is always 0. The values after that is always going to be the sum of col2 + col3 of the previous record.

col1  col2   col3
1     6.48   0
2     1.95
3     1.66
4     .84
5     .56
6     1.24

So the final values would be as follows:

col1  col2     col3
   1     6.48    0
   2     1.95    6.48
   3     1.66    8.43
   4     .84    10.09
   5     .56    10.93
   6     1.24   11.49

Does anyone know if this can be done without a cursor in SQL Server?

Answer 1

You could use windowed SUM and subtract current value:

SELECT *, SUM(col2) OVER(ORDER BY col1)-col2 AS col3
FROM tab;

db<>fiddle demo