use BalloonShop
select * from Product


--20個字，1， 5
CREATE PROCEDURE GetProductsOnCatalogPromotion
(@DescriptionLength INT,--描述信息長度
@PageNumber INT, -- 第幾頁
@ProductsPerPage INT, --每頁顯示幾個商品
@HowManyProducts INT OUTPUT -- 一共有多少商品
)
AS
-- declare a new TABLE variable
DECLARE @Products TABLE --表變量
(RowNumber INT
 
, --在products原始表上增加一個可靠的編號字段
 ProductID INT,
 Name VARCHAR(50),
 Description VARCHAR(5000),
 Price MONEY,
 Image1FileName VARCHAR(50),
 Image2FileName VARCHAR(50),
 OnDepartmentPromotion BIT,
 OnCatalogPromotion BIT)

-- populate the table variable with the complete list of products
INSERT INTO @Products
SELECT
 
 ROW_NUMBER() OVER (ORDER BY Product.ProductID),
       ProductID, Name, 
       SUBSTRING(Description, 1, @DescriptionLength) + ‘...‘ AS Description,
       Price, Image1FileName, Image2FileName, OnDepartmentPromotion, OnCatalogPromotion
FROM Product
WHERE OnCatalogPromotion = 1

-- 給輸出參數@HowManyProducts賦值
 

SELECT @HowManyProducts = COUNT(ProductID) FROM @Products

-- extract the requested page of products
-- 把請求的第幾頁的內容從@Products表變量中查詢出來
SELECT ProductID, Name, Description, Price, Image1FileName,
       Image2FileName, OnDepartmentPromotion, OnCatalogPromotion
FROM @Products
WHERE RowNumber > (@PageNumber - 1) * @ProductsPerPage
  AND RowNumber <= @PageNumber * @ProductsPerPage
GO

use BalloonShop

--理解表變量
DECLARE @Products TABLE
(RowNumber INT,
 ProductID INT,
 Name VARCHAR(50),
 Description VARCHAR(5000),
 Price MONEY,
 Image1FileName VARCHAR(50),
 Image2FileName VARCHAR(50),
 OnDepartmentPromotion BIT,
 OnCatalogPromotion BIT)
INSERT INTO @Products    
SELECT  Row_number() OVER (ORDER BY ProductID) , * from Product where OnCatalogPromotion = 1

select * from @Products
go

use BalloonShop
declare @HowManyProducts int
exec GetProductsOnCatalogPromotion 15,2,6, @HowManyProducts out 
select @HowManyProducts

--一共多少頁：總商品數/每頁的產品數 (小數) = 2.1
-- ceiling 

分頁存儲過程（代碼）