How do I compare the contents of a series of columns in each row for exact
matches in other rows?

e.g. for row 2 compare the contents of columns B,C,D & F against all the
other rows' columns B,C,D & F and if an exact match is found highlight, or
spike, the contents. Then check row 3, row 4, etc.

I was thinking maybe to concatenate each of the row's columns into a string
and the do the same with the other rows to find a match.

Please help, I really need to do this exercise on a large database.