-- zad 1

SELECT C.CustomerID, C.CompanyName
FROM Customers C
WHERE C.CustomerID NOT IN (SELECT O.CustomerID FROM Orders O)

-- Zad 2
SELECT E.EmployeeID, sum(OD.UnitPrice * OD.Quantity) as 'sum'
FROM Employees E JOIN Orders O ON E.EmployeeID=O.EmployeeID
		JOIN [Order Details] OD ON O.OrderID=OD.OrderID
GROUP BY E.EmployeeID
HAVING COUNT (distinct OD.ProductID) > 50
ORDER BY E.EmployeeID

-- ZAD 3
SELECT E.LastName,
		YEAR(O.OrderDate) rok,
		MONTH(O.OrderDate) msc ,
		CASE WHEN grouping(YEAR(O.OrderDate)) != 0 THEN '0' ELSE  YEAR(O.OrderDate) END,
		CASE WHEN grouping(MONTH(O.OrderDate)) != 0 THEN '0' ELSE  MONTH(O.OrderDate) END,
		CASE WHEN grouping(DAY(O.OrderDate)) != 0 THEN '0' ELSE  DAY(O.OrderDate) END,
		 SUM(OD.UnitPrice * OD.Quantity) suma
FROM Employees E JOIN Orders O ON E.EmployeeID=O.EmployeeID
		JOIN [Order Details] OD ON O.OrderID=OD.OrderID
WHERE E.LastName = 'Buchanan'
GROUP BY E.LastName, rollup(YEAR(O.OrderDate), MONTH(O.OrderDate), DAY(O.OrderDate), OD.ProductID)