SELECT DISTINCT
P.FirstName + ' ' + P.LastName AS Klient,
YEAR(SOH.OrderDate) AS Rok,
MONTH(SOH.OrderDate) AS Miesiac,
COUNT(*)
OVER(PARTITION BY C.CustomerID, YEAR(SOH.OrderDate),
MONTH(SOH.OrderDate)) AS [W misiacu],
COUNT(*) OVER(PARTITION BY C.CustomerID, YEAR(SOH.OrderDate)) "W roku",
COUNT(*) OVER(PARTITION BY C.CustomerID, YEAR(SOH.OrderDate) ORDER BY
MONTH(SOH.OrderDate)) AS "W roku narastajaco"
FROM Sales.Customer C
JOIN Person.Person P ON C.PersonID = P.BusinessEntityID
LEFT JOIN Sales.SalesOrderHeader SOH ON C.CustomerID = SOH.CustomerID
LEFT JOIN Sales.SalesOrderDetail SOD ON SOH.SalesOrderID = SOD.SalesOrderID
Order By 1,2,3