validation for three input fields
 

Hi all,

I would like to do validation on three fileds' combination in order to make
them unique, for example in following case the row1 and row2 input
combination(A, B, C) is same so it is not allowed.
A B C D
1 1 2 3 =A1&B1&C1
2 1 2 3 =A2&B2&C2


what I do is add formula in colum D to get the combination of A,B,and C and
use a validation fomula like: =countif(&D&1:$D$2, D1)=1 to force the
uniqueness, but it does not work as assumed.

Clara

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thank you so much for your help