Eu aş face toate calculele în Transact-SQL, de exemplu (în baza de date AdventureWorks):

DECLARE @StartDate datetime, @EndDate datetime
SET @StartDate='20031001'
SET @EndDate='20031231'

SELECT * FROM (
  SELECT YEAR(OrderDate) AS YearNumber, MONTH(OrderDate) AS MonthNumber, DAY(OrderDate) AS DayNumber,
    OrderDate, WeekDayName, CurrentSales, PreviousYearDate,
    (SELECT SUM(TotalDue) FROM Sales.SalesOrderHeader WHERE OrderDate=PreviousYearDate) AS PreviousYearSales
  FROM (
    SELECT OrderDate, WeekDayName, CurrentSales,
      DATEADD(DAY,(DATEPART(WEEKDAY,OrderDate)-DATEPART(WEEKDAY,DATEADD(YEAR,-1,OrderDate))+7)%7,DATEADD(YEAR,-1,OrderDate)) AS PreviousYearDate
    FROM (
      SELECT OrderDate, DATENAME(WEEKDAY,OrderDate) AS WeekDayName, SUM(TotalDue) AS CurrentSales
      FROM Sales.SalesOrderHeader
      WHERE OrderDate BETWEEN @StartDate AND @EndDate
      GROUP BY OrderDate
    ) t1
  ) t2
  UNION ALL
  SELECT YearNumber, MonthNumber, NULL AS DayNumber, NULL AS OrderDate, NULL AS WeekDayName, CurrentSales, NULL AS PreviousYearDate,
    (SELECT SUM(TotalDue) FROM Sales.SalesOrderHeader WHERE YEAR(OrderDate)=YearNumber-1 AND MONTH(OrderDate)=MonthNumber) AS PreviousYearSales
  FROM (
    SELECT YEAR(OrderDate) AS YearNumber, MONTH(OrderDate) AS MonthNumber, SUM(TotalDue) AS CurrentSales
    FROM Sales.SalesOrderHeader
    WHERE OrderDate BETWEEN @StartDate AND @EndDate
    GROUP BY YEAR(OrderDate), MONTH(OrderDate)
  ) t3
) t4
ORDER BY YearNumber, MonthNumber, -DayNumber DESC

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