-- Database schema
| Customers : CustomerID [ INTEGER ] primary_key , FirstName [ TEXT ] , MiddleInitial [ TEXT ] , LastName [ TEXT ] | Employees : EmployeeID [ INTEGER ] primary_key , FirstName [ TEXT ] , MiddleInitial [ TEXT ] , LastName [ TEXT ] | Products : ProductID [ INTEGER ] primary_key , Name [ TEXT ] , Price [ REAL ] | Sales : SalesID [ INTEGER ] primary_key , SalesPersonID [ INTEGER ] Sales.SalesPersonID = Employees.EmployeeID , CustomerID [ INTEGER ] Sales.CustomerID = Customers.CustomerID , ProductID [ INTEGER ] Sales.ProductID = Products.ProductID , Quantity [ INTEGER ] |
-- -- What is the best selling colour for HL Mountain Frame, 42?

SELECT IIF(SUM(IIF(T1.Name = 'HL Mountain Frame - Silver, 42', T2.SalesID, 0)) - SUM(IIF(T1.Name = 'HL Mountain Frame - Black, 42', T2.SalesID, 0)) > 0, 'Silver', 'Black') FROM Products AS T1 INNER JOIN Sales AS T2 ON T1.ProductID = T2.ProductID;