Question: Calculate the total trading quantity of Abraham sold to Aaron Alexander.
SQL: SELECT SUM(T2.Quantity) FROM Customers AS T1 INNER JOIN Sales AS T2 ON T1.CustomerID = T2.CustomerID INNER JOIN Employees AS T3 ON T2.SalesPersonID = T3.EmployeeID WHERE T2.SalesPersonID = 1 AND T1.FirstName = 'Aaron' AND T1.LastName = 'Alexander' AND T3.FirstName = 'Abraham'