A user can add column to the table where the program sort

Question

a user can add column to the table ,where the program sort them and display them sorted ,with sort i mean by row not order by;

order by is easy but sorting rows is harder,the difficultly comes with the fact that the user can add colums where the program

should do the sort and display them in gridview.

column1      column2          column3        column4

    8                 7                     9                 1

    6                 3                     1                  2

    5                 2                     4                  3

    8                 6                     3                  1

so the answer should be

column1       column2      column3            column4       column5

       8              7                 9                      1               1-7-8-9

       6              3                 1                      2               1-2-3-6

       5              2                 4                      3               2-3-4-5

       8              6                 3                      1               1-3-6-8