Data Entry - Avoid Duplicates

[kvc]

Is there anyway to set an alert or validation.. to avoid duplicates?

For example:

columnA
abc123
abc122
abc133
abc124


If someone were to add a next entry and tried to type abc123 or any of
the other values listed.. an alert would come up and prevent them from
entering a value that's already listed??

Sort of like in Microsoft Access using a Primary key... if you tried
to enter a primary key that's already in the table.. access won't let
you...

Can this be done in Excel?

Thanks for all your help!

 

[Bob Phillips]

Use Data Validation, with a custom type and a formula of

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

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HTH

Bob

(there's no email, no snail mail, but somewhere should be gmail in my addy)

 

[Ron de Bruin]

Hi kvc

See
http://www.cpearson.com/excel/NoDupEntry.htm