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!

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

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

--
---
HTH

Bob

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



"kvc" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> 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!
>

Hi kvc

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


--

Regards Ron de Bruin
http://www.rondebruin.nl/tips.htm


"kvc" <(E-Mail Removed)> wrote in message news:(E-Mail Removed)...
> 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!
>