Automatic Sort using a formula

Hi All

Need some help please...

I have two columns which I need to be able to sort automatically without selecting the data, copy and pasting it and then sorting it manually. Can this be done with a formula?

The customer names are in column D and the ranking field is in column E on my "Summary" sheet. Can it be set up so that the last row is found e.g.

=INDEX(Summary!$D:$D,ROW(Summary!$D$4)+1):INDEX(Summary!$D:$D,Last_Row)

I have attached an example file - I would need the formulas to be placed in the yellow coloured fields.