>>>In my prev. job I had some code to check for uniqueness at the class level using Indexseek as Cetin suggested (actually, I had the code twice in valid of textbox and in save time). If you want, I'll search for that old code...
>>
>>Hi N,
>>
>>An indexseek is not that reliable in a multiuser environment. I'd say you need a candidate index on the base table. - not on the view since it's a local copy which may/will be out of date
>
>Interestingly, I'm currently in need of this functionality. I'm thinking, what would be the best way to handle the situation? I'd like to be able to notify the user right away in the textbox Valid and on the Save as well. On the Save I can probably trap for the error, but how exactly would I know, if I'm not changing an existing field to an exisiting entry (but different record)?
>
>What are your thoughts here?
>
>Thanks in advance.
>
>This seems logical enough:
>

>thisform.addmode and oldval(lcfield,lcAlias)<>lcvalue)
>* Note - the select only sees the values already on disk (not buffered)
>		      lcSavDel=SET('DELETED')
>		      SET DELETED OFF
>
>		select * from (lcAlias) ;
>		where &lcfield == lcvalue to screen noconsole
>	         SET DELETED &lcSavDel.
>
>		*!*	*--- Test results of SELECT-SQL duplicate record check.
>
>				if _tally > 0
>					llunique = .f.
>				endif
>

________
That's an old one ...

If you want a kind of warning during the edit, I would

(1) Not check on addmode, ie one can change a field as well

(2)
If ( FieldChanged(... ) )
    lcSavDel=SET('DELETED')  && only if indexexpr is not filtered on deleted()
    SET DELETED OFF
    AlreadyThere = indexseek(IndexExprWithThisValue, FALSE, BaseTableNameInCaseOfView, IndexTag)
    SET DELETED &lcSavDel
endif

You have a candidate index on the base table

Personally, I find this too much coding and would only trap the error on the Save()
If the error message is meaningful and for the few times it would occur, I don't see any problem with that

Also, if the index is based on more than one field you would have this kind of checking in more than one textbox
I'd go for a subclassed textbox if I had to do it