I don’t know if I understand your question.
Is it because you are trying to update a value based on a certain value in the first column?
You should look into Dictionaries. Dictionary will store each value into like a data map where you can access it through a key. This can be used in UiPath through Assigning/Initializing the dictionary then storing values to it, and there are many examples on these forums or online.
You can still use a Data Table in the same way, however, because you can filter to the row based on your keyword (utilizing vb.net coding) then Assign a value to that row.
So those are a few thoughts on it.