DECLARE @AllData TABLE =
(
    SELECT Employees.EmployeeFirstName+Employees.EmployeeLastName as Employee, COUNT([Order Details].OrderID) as Counter, SUM([Order Details].UnitPrice*[Order Details].Discount*[Order Details].Quantity) as Pricer
    FROM Employees, Orders, [Order Details], Products
    WHERE
        Employees.EmployeeID = Orders.EmployeeID AND
        Orders.OrderID = [Order Details].OrderID AND
        [Order Details].ProductID = Products.ProductID
)

DECLARE @MaxCount int = SELECT MAX(Data.Counter) FROM @AllData as Data
DECLARE @MaxPrice real = SELECT MAX(Data.Pricer) FROM @AllData as Data
DECLARE @MinCount int = SELECT MIN(Data.Counter) FROM @AllData as Data
DECLARE @MinPrice real = SELECT MIN(Data.Pricer) FROM @AllData as Data

SELECT Data.Employee, [Best COUNT], @MaxCount FROM @AllData as Data WHERE Data.Counter = @MaxCount
UNION
SELECT Data.Employee, [Best REVENUE], @MaxPrice FROM @AllData as Data WHERE Data.Pricer = @MaxPrice
UNION
SELECT Data.Employee, [Worst COUNT], @MinCount FROM @AllData as Data WHERE Data.Pricer = @MinCount
UNION
SELECT Data.Employee, [Worst REVENUE], @MinPrice FROM @AllData as Data WHERE Data.Pricer = @MinPrice