How do I combine rows?

[JoseC]

I have rows with a unique id and number of years they were active. There are in some cases two rows with the same id and I would like to combine the rows so there is only one indicator and the years combine into a sum.

[art297]

You probably want to use proc summary with ID as a by variable, but you would have to provide some info about your data to get more specific guidance.  It always helps to provide a sample data file (in datastep form), along with your desired result, to get the best feedback.