Database Design

I want to design a database keeps track of customers for example a customer's age, sex, state etc. However I don't want the table fixed. In other words if in two weeks I decide to add a new field such as the customer's email i don't want to add a new column to the database, I want to be able to use the initial design. I'm new at this , and currently what i'm thinking about is having a table with the following columns

customer_name | attribute | value (all nvarchar)

so that anytime there is a new value that i need to add i just describe it in the attribute column and specify the value in the value column. So for instance i could specify the customer's email as:

jack | email | jack_at_a.com

however i have a new problem now, which is if jack has more than one email address that means i should make all three columns part of the primary key so that i could insert

jack | email | jack_at_a.com
jack | email | jack_at_b.com

this seems kind of weird to me. If anyone has some advice on how to design a database like this please let me know.

Thanks a lot.

Ralph Received on Sat Sep 15 2001 - 21:13:43 CEST