This example creates a query that joins the Customers and Orders tables on the CustomerID field. The Customers table contains no duplicate CustomerID fields, but the Orders table does because each customer can have many orders. Using DISTINCTROW produces a list of companies that have at least one order but without any details about those orders.
SELECT DISTINCTROW CompanyName
FROM Customers INNER JOIN Orders
ON Customers.CustomerID = Orders.CustomerID
ORDER BY CompanyName;