Final answer:
The primary method for dealing with a combined result set from a federated query is to use a SQL JOIN operation.
Step-by-step explanation:
The primary method for dealing with a combined result set from a federated query is to use a SQL JOIN operation. A JOIN allows you to combine rows from two or more tables based on a related column between them. This can be done using different types of joins such as INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN.
For example, if you have two tables named 'Customers' and 'Orders' and you want to combine them based on the 'customer_id' column, you can use an INNER JOIN like this:
SELECT * FROM Customers INNER JOIN Orders ON Customers.customer_id = Orders.customer_id;