ALTER Procedure OrdersDetail
(
@OrderID int,
@UserID int,
@OrderDate datetime OUTPUT,
@OrderTotalCost money OUTPUT
)
AS
SELECT
@OrderDate = OrderDate

FROM
Orders

WHERE
OrderID = @OrderID
AND
UserID = @UserID
IF @@Rowcount = 1
BEGIN
SELECT
@OrderTotalCost = Cast(SUM(OrderContent.BookQuantity * OrderContent.UnitCost) as money)

FROM
OrderContent

WHERE
OrderID= @OrderID
SELECT
Book.BookID,
Book.BookName,
Book.ISBN,
OrderContent.UnitCost,
OrderContent.BookQuantity,
(OrderContent.BookQuantity * OrderContent.UnitCost) as ExtendedAmount
FROM
OrderContent
INNER JOIN Book ON OrderContent.BookID = Book.BookID

WHERE
OrderID = @OrderID
END

请 帮我指点下 红色的语句都是什么意思啊
还有正篇的语句的意思

请再给点这方面的语句的资料啊
谢谢大家了

IF @@Rowcount = 1 是如果前面那个查询语句有结果，并且影响的行数是1行，就开始执行你下面的语句，SUM(OrderContent.BookQuantity * OrderContent.UnitCost)是数据库中两个字段的乘积，as money是将乘积转换为money型，即货币型的，前面的函数cast就是转换类型用的，INNER JOIN Book ON OrderContent.BookID = Book.BookID
是关联表查询，即让你前面查询的表和这个表的内容同时可以查出来，通过共同的ID

3ks very much