SELECT O.ID, C.SecondName AS [Фамилия клиента], E.SecondName AS [Фамилия Сотрудника], O.DateOf AS Дата, P.Title AS Продукт, P.CurrentPrice AS Цена, O.Quantity AS Количество, SUM(P.CurrentPrice*O.Quantity) AS Сумма
FROM ((Client AS C INNER JOIN [ORDER] AS O ON C.ID = O.ClientID)
INNER JOIN Employee AS E ON E.ID = O.EmployeeID)
INNER JOIN Product AS P ON P.ID = O.ProductID
GROUP BY O.ID, C.SecondName, E.SecondName, O.Dateof, P.Title, P.CurrentPrice, O.Quantity