Write Data to excel in specific column as per matching Row

I have data in Datatable. Let’s say -

Column A, Column B, Column C

in Excel

Column A, B, C, D

I have to write to Column D depending on matching record in Datatable and Excel based on Column A.

Like write to excel column based on condition for specific rows.

I belive this issue How to copy specific rows from a excel to new excel based on condition - #7 by vickydas is rather similar. You still need to make a few modifications but i hope it helps. If you encounter problems please tell.