Sounds like you need to investigate one-to-many and many-to-many
realtionships. In short, you would not use data from one table in another
table. You could create a relationship (link) to tie data from the various
tables together. This is the purpose of a relational database.
For example, you might have one table with customer data (including an
account number).
Then you might have another table with Products (including a stock number).
You might have still another table with invoice headers (which would contain
an invoice number and the customer account number.) If a customer has two
invoices created, they would have two records in this table. Each record
would contain the same customer number, but a different unique invoice
number. It might also have the invoice date, and the salesperson number who
created the invoice. (of course, there'd be another table that contained
all the valid salesperson numbers and more details about them such as name,
extension, commission rate, etc.
You could have still another table that had the invoice details. It would
include the invoice number, and the stock number ordered by the customer.
If they ordered two products, they'd have two entries in this table.
You might take a look at the Northwinds sample database that comes with
Access to get a better feel for how relationships work.
Post back specific details if you need specific help.
Rick B