14. Which day of the week (Sun/Mon/…) has the highest total sales value? Hint: In Access use the function Format(date, "ddd") to obtain the day of the week.
SELECT Format([SaleDate],"ddd") AS Weekday,
Sum([Quantity]*[SalePrice]) AS SalesValue
FROM Sale INNER JOIN SaleItem ON Sale.SaleID = SaleItem.SaleID
GROUP BY Format([SaleDate],"ddd")
ORDER BY Sum([Quantity]*[SalePrice]) DESC;