Multiple composition of beans or beans as interface

In my company we have tables, beans for those tables, and SQL requests using those beans as output and those table as input (iBatis, myBatis, ..).

As usual, I create an entity bean for each table I use in an application.

But where a SQL request is using 7 tables, for example, I need to create a composition of 7 beans. And if another request is using 4 different table, I have to create another composition of 4 beans.

Now I'm wondering if I need to have as many compositions as multiple table tuples in requests the application has.

I thought about beans as interface to solve this problem but it doesn't seem to be possible.

Example of the problem :

Tables CUSTOMER, CAR, CUSTOMERCAR, RETAILER, CUSTOMERRETAILER, ...

SELECT customer.name, retailer.name, car.name WHERE ...

To handle this request output for those entities :

public CustomerRetailerCar {

    private Customer customer;
    private Car car;
    private Retailer retailer;

}

So I end up with a lot of compositions and I'm feeling I'm not solving this problem the right way. Am I wrong?

Any advice appreciated.