SQL Adding quantity of another column

Question

I need to compute the sum of a column (B) in another column (C), but adding the next value and changing taking into account another column criteria (A), something like this:

Is this possible with a simple SELECT?

Answer 1

In SQL Server, the window function sum() over() should do the trick.

Note the order by ColB ... This is just a placeholder, I suspect you have another column which would have the proper sequence

Example

Select ColA
      ,ColB
      ,ColC = sum(ColB) over (partition by ColA order by ColB rows unbounded preceding )
 From  YourTable