To do that you can take one of two appoaches depending on whether you can copy data from an old table, say my_old_table, to the corresponding new table, say my_new_table, using a simple SELECT statement.
If you can do so, your best bet is to write CREATE TABLE statements and execute them against your customer's database so that it contains the old tables + data in them + new tables. Now simply execute SELECT statements to bulk-copy data from the old tables to the new ones.
If you cannot do so, however, the method I just described is not the way to go. In this case, you should create a separate database with the new structure. Then write a VB
program that processes each table sequentially and dumps data from the old database to the new one. If you do take this approach, be sure to take care of any constraints. For example, you'll have to copy data to a parent table before
you can copy data to a child table, a table whose records reference records in the master table. After data is copied to the new database, delete the old database.
In either case, be sure to have your database backed up, just to be on the safe side.
I hope this helps.