best practice for lookup

say i have a customer.aspx that allows a user to enter in customer data.

on customer.aspx, i have dropdownSalesRep which allows the user to associate a sales rep with the customer

but some customers come to directly, and not thru a sales rep, so I want the user to be able to specify "none"

Is it best to have a dummy record in my SalesReps table called "none" with an ID of say "999", or is there some other better way to deal with this?

I think this is more of a business decision. When you have to do reporting later on to track the sales, would you want to see "none" under sales rep?

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well, probably not, so assuming you don't - then is there even another way dealing with it assuming that in the underlying db, a customer must have an associated sales rep? in that reporting scenario, you'd have to write sql to filter out the "dummies" i guess.

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NuJoizey:

...assuming that in the underlying db, a customer must have an associated sales rep?

If you have to code according to that assumption, then you really have no choice than to use some sort of default value in your application with an Id of "999" or whichever you are comfortable with. Jjust make sure it doesnt get repeated. You can also use a negative value like -1 so there is no conflict with any number generated by SQL Server if your table grows.

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Another way to handle this is to store NULL in the sales rep ID. This is, in a sense, the more elegant solution since NULL means not known and you can do this and still maintain the foreign key relationship with your sales rep master table

However, many people don't like using NULL values because of their unintuitive behavior in select statements (eg, "select * from customer where SalesRepId <> 3" will NOT return rows where SalesRepId is NULL because NULL= unknown and if something is unknown it justmight be 3).

My advice is to follow ndinakar's suggestion and use a special value like -1

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great - thank you for the discussions