- I need to automatically calculate a field based on values from previous rows?I need to automatically calculate a field based on values from previous rows such that once the total of all the previous rows is greater than 450 and less than 500, the next row starts counting from 0 or the balance of what made the previous row greater than 500. The script below just calculates the sum of the cities point that falls within the county, I want something that would make the value of a row (i.e. row2) the addition of the value of row1 + value of row2 and so on till when it gets to 500, where it starts from 1 again. Kindly help me please.

Could you expand on your example so we may get a better understanding of what you are trying to do?