Create time range for each customer from adjacent time

Hi, Originally I generated a table from a Splunk query in the following form: CustomerID SeenTime 1234 8/5/2015 1234 8/19/2015 1234 9/1/2015 2345 10/3/2015 2345 10/9/2015 Now, I would like to create a time range for each row of each customer using the current row's Seen Time as min_SeenTime and the next row's seen time as max_SeenTime. If there is no next row seen time for the customer, then use the today's date. For this specific example, I would like to generate the following result: CustomerID Min_SeenTime Max_SeenTime 1234 8/5/2015 8/19/2015 1234 8/19/2015 9/1/2015 1234 9/1/2015 Today's Date 2345 10/3/2015 10/9/2015 2345 10/9/2015 Today's Date Could someone please help me how to realize this? Thanks a lot! Wayne