[AccessD] One-to-One relationships

Yes, if it has a purpose. A one-to-one relationship almost always flows from
need rather from the data itself. If you need to force a one-to-one, I'd say
do it. However, if there's no business rule saying, "there can be only
one..." it might be unnecessary, even if the data is presenting that picture
right now. Listen to the data. 

Susan H. 

Is there any purpose/advantage in creating a one-to-one relationship in a
database (e.g., CustomerId and CustomerName in one table and all the other
customer data (e.g., sex, address,  phone, etc) in another table?