How can I fill in values for a field based on common ID number?

[thepinkgeologist]

So, I have huge excel datasets where there are fields for well number, latitude and longitude and then thousands of entries.

Many of the wells only have lat and long entered for some of their fields, and the others say "unknown" even though it clearly is NOT unknown. (see attached screenshot)

I want to fill in the "unknown" with the correct elevation, lat and long that exists in other fields in those columns (columns4 through 6) for that well number in column 2.

I can do this by hand by I have many files and they are all early 1 million rows long ... is there a quicker way?