This is not possible just through Crystal unless you have a very limited list of Customers and you're willing to change the report everytime you add, change, or delete a customer. Then whether or not it's possible would depend on your table structures and how things link together.
How are you delivering the report? If you're writing a web or Windows application and the fields in the tables all have the same names, then you could have the user chose the customer as part of your application and then dynamically set the table name(s) on the report before running it.
-Dell