Column A (number)       ColumnB (String)    Date
666                    John                 6/14/19
666                    Mark                 6/10/19
666                    Joe                  6/20/19
999                    David                5/12/19
999                    Mark                 4/12/19
999                    John                 6/20/19
...                    .....                 ....

Number    John  Mark   Joe   David
    666    X      X     X      Y
    999    X      X     Y      X