Validiation

H

Haitham

i want from you to think about if i have a column and the user have put
inside one of the cells of the column a value , and the user enter this value
again inside another cell in the same column.
My problem is that i want to make a condition that this value that have been
entered by this user in the first cell , will not be entered again in any
cells.
(this problem because i want to make a column of a header serial #)
 
K

Ken Johnson

Hi Haitham,

For serial numbers in column A...

Custom Formula..

=COUNTIF($A:$A,A1)<=1

Ken Johnson
 
K

Ken Johnson

Hi Haitham,

I forgot to add that this formula is used with data validation.

Go Data|Validation... select "Custom" from the drop down list in the
"Allow:" box, then type the formula in the "Formula:" box, then OK.

Ken Johnson
 
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