ALERT IF TRY TO ENTER SAME SECOND TIME

D

dancer

I need to enter data in about 10 columns from hard copies I get daily. One
of these columns will be a key (alphanumeric) that defines a job. I may
receive other hard copies on other days of that same job. I don't want to
enter the data a second time. How can I have the sheet alert me if I try
to enter the key again?
 
T

T. Valko

You can data validation for this.

Suppose the range in question is A1:A10

Select the range A1:A10
Goto the menu Data>Validation
Allow: Custom
Formula:

=COUNTIF(A$1:A$10,A1)<=1

Ok

Whenever you attempt to *manually* enter a duplicate value a message box
will pop up and alert you. This can be defeated by copying/pasting and/or
drag/drop.

Biff
 
D

dancer

WONDERFUL! Now, please explain the formula. I just can't understand how
it works.

Thanks
 
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