How would YOU do it?

Question

Please help me with an idea. I have a dynamically populated datagrid with 3 sortable columns: Last Name, First Name, Age. I need to add another column '#' which values will never change even if user sorts by other columns. Example: # Last Name First Name Age 1 Doe John 29 2 Loe Joe 28 3 Moe Jerry 35 Now, if user sorts by age, this is what I want the output to be: # Last Name First Name Age 1 Loe Joe 28 2 Doe John 29 3 Moe Jerry 35 See, only 3 columns get sorted. Column "#" is ALWAYS the same. Number of people is always different, depending on the company. What would be the easiest way to accomplish this. Thank you all in advacne.