Hi all,

I am creating a spreadsheet which will have data entry from different
users.

I want to give the validation in such a way that a combination of
values in 2 columns do not occur more than once.

Like say
A B
1 a
1 b
2 a
2 b
2 a

in above example the combination 2 and a is recurring. it should be
restricted by validation while entering the data itself.

can anybody please help

Regards
NC