创建存储过程GetOrdersDetail取得订单详细信息，输入参数为订单号OrderId和用户号UserId，输出参数为订单日期OrderDate和该订单总金额Quantity *UnitCost。要求：如果存在相应的订单信息，则首先通过输出参数返回订单总金额，然后查询该订单详细信息。

CREATE PROCEDURE GetOrdersDetail
@OrderId INT,
@UserId INT,
@OrderDate DATE OUTPUT,
@TotalAmount DECIMAL(10,2) OUTPUT
AS
BEGIN
SET NOCOUNT ON;

-- Check if order exists for given user
IF EXISTS (SELECT 1 FROM Orders WHERE OrderId = @OrderId AND UserId = @UserId)
BEGIN
-- Calculate total amount for given order
SELECT @TotalAmount = SUM(Quantity * UnitCost)
FROM OrderDetails
WHERE OrderId = @OrderId

-- Get order date for given order
SELECT @OrderDate = OrderDate
FROM Orders
WHERE OrderId = @OrderId AND UserId = @UserId

-- Get order details for given order
SELECT *
FROM OrderDetails
WHERE OrderId = @OrderId
END
ELSE
BEGIN
-- Return error message if order does not exist
RAISERROR('Order does not exist for given user.', 16, 1)
END
END
GO