Ok lets say I have a table of customers and states. I want the end
user to have a choice in inputing a state for a given customer. Since
state is used as a lookup table with a foreign key used in customer,
how can I have a blank as a state name and still keep it all unique?

here is a sample of what the tables look like

customer(custNo,name,address,cityNo,stateNo,countryNo,postal)

state(stateNo,name)

custNo and StateNo are primary indexes and use a generator, the user
never enters these values.

I have used a unique index on the (state)name and allowed nulls,
which I now understand will not work. I do not want to use a space as
a work around, so how do I get there from here?

Also I am using Delphi's data aware controls...