Suppose I have sorted sample dataset looks like this   CustomerID   CallID  Date 123                1          01/30/2017 123                2          01/30/2017 123                3          02/03/2017 123                4          02/07/2017 123                5          02/08/2017   I want to count how many calls did I received from the same customer in the past 7 days as of each date. The desired output dataset would be   CustomerID   CallID  Date                    NumOfCallsInOneWeek 123                1          01/30/2017         1 123                2          01/30/2017         2 123                3          02/03/2017         3 123                4          02/07/2017         2 123                5          02/08/2017         3   Note as of 02/07/2017, the 2 calls on 01/30/2017 are received over a week ago, so they are not counted. How could I do it using either data step or proc sql? Could someone please help me? I'd really appreciate it!!! Thank you! ... View more