I'd like to know the easiest way to make sure that only unique strings are entered in a particular column in MS Excel 2007? I know I have to put a formula in the Data > Data Validation, but I don't know how.
Say, I'm entering data anyplace within column B, and I want to know if the inputting value is already elsewhere in the column (above or below the current cell) and don't allow if there is a duplicate.
I've seen answers like this one on this site, but they all have an range say from B1 to B20, how do I have this validation on the entire column, is this possible?
Seem like when I drag on the cell, duplicated values can appear, it is only when I try to input the value that this validation works. So, how do I restrict on the dragging as well as manual input on this?