related fields

[Pat Smith]

Please can someone explain to me how I do the following: I
have a table of customer names and a table of products.
The product table has two columns: product name and VAT
rate. In the customer names table I have a column which
is a look-up for the products so I can select which
product the customer has bought. Question: how can I get
the correct VAT rate for the product from the products
table to automatically populate into another column in the
customer table when I select the product?

thanks a million
Pat