There's not much point processing the data before you've got anywhere to put it. If you read what I posted in your other thread you'll see that I said to add the new column first. You can then loop through the rows and, for each row, get the data from the source column, process it and then put the result into the destination column. You've got all the pieces there. You just need to arrange them into the proper order.

Whenever you write code, the code you write must implement the steps you should already know that your app needs to perform. If you try to write the code first, the likelihood that it will do what you want is low, because you don;t even know what you want yourself.