How to create a column with no duplicate entries

  • Thread starter Thread starter Guest
  • Start date Start date
G

Guest

I have a column which is blank at the moment but which I will be using to input invoice numbers. I want there to be no invoice numbers the same - i.e. no duplicate entries within the column itself. There is no formula in the column because it is a number I just input from the invoice.
 
Hi

Select the column (p.e. column A)
Data.Validation.Custom
Formula=COUNTIF(A:A,"=" & A1)<2
Press Enter

It's all



Ita said:
I have a column which is blank at the moment but which I will be using to
Click to expand...
input invoice numbers. I want there to be no invoice numbers the same -
i.e. no duplicate entries within the column itself. There is no formula in
the column because it is a number I just input from the invoice.
 
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