我想此時不妨使用字符串參數來幫助我們解決這種情況，利用字符串分割的方法將一個參數分割成數個參數來解決。下面我們看一個例子：
假設現在給你一個產品信息列表（顯示出各個商品的基本信息），現在我想要根據所選擇商品進行統計（任意選擇幾種），例如統計出價格<10,11-20,21-30,31-40,41-50,50以上的商品個有多少個（姑且認為就統計這些）。此時如果使用存儲過程就勢必需要傳入所選商品的id作為參數，但是id個數是不固定的。此時估計會有人這樣寫：
復制代碼 代碼如下:
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author: jianxin160
-- Create date: 2010.11.05
-- Description: 統計商品
-- =============================================
ALTER PROCEDURE StatProductInfo
(
@ids VARCHAR(8000)
)
AS
BEGIN
DECLARE @followingTen INT
DECLARE @elevenToTwenty INT
DECLARE @twentyOneToThirty INT
DECLARE @thirtyOneToFourty INT
DECLARE @fourtyOneToFifty INT
DECLARE @fiftyOrMore INT
SELECT @followingTen=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(@ids) AND UnitPrice<10
SELECT @elevenToTwenty=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(@ids) AND UnitPrice BETWEEN 11 AND 20
SELECT @twentyOneToThirty=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(@ids) AND UnitPrice BETWEEN 21 AND 30
SELECT @thirtyOneToFourty=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(@ids) AND UnitPrice BETWEEN 31 AND 40
SELECT @fourtyOneToFifty=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(@ids) AND UnitPrice BETWEEN 41 AND 50
SELECT @fiftyOrMore=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(@ids) AND UnitPrice>50
SELECT @followingTen AS '<$10',@elevenToTwenty AS '$11-$20',
@twentyOneToThirty AS '$21-$30',@thirtyOneToFourty AS '$31-$40',
@fourtyOneToFifty AS '$41-$50',@fiftyOrMore AS '>$50'
END
GO
其實如果你測試一下（例如：EXEC dbo . StatProductInfo '3,4,8,10,22' ）是有問題的，sql server認為這整個是一個參數，轉換時出錯。此時我們想一下如果這些字段在一個虛表中就容易操作多了，但是一般虛表是有其他表通過查詢得到，現在根本無法查詢又哪來的虛表呢？聰明的朋友或許已經想到可以使用"表值函數"。對，答案就是使用"表值函數"。我們知道"表值函數"可以返回一個"Table"類型的變量（相當于一張虛表，存放于內存中），我們首先將字符串分割存放到"表值函數"的一個字段中，然后我們再從"表值函數"中查詢就可以了（這個例子也是"表值函數"的一個典型應用）。具體sql如下：
復制代碼 代碼如下:
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author: cmj
-- Create date: 2010.11.05
-- Description: 返回一個Table,只有一列，每一行的數據就是分割好的字符串
-- =============================================
CREATE FUNCTION GetSplitFieldsByString
(
@toSplitString varchar(1000),
@splitChar varchar(10)
)
RETURNS
@tb TABLE(sp varchar(100))
AS
BEGIN
DECLARE @i INT
SET @toSplitString=RTRIM(LTRIM(@toSplitString))
SET @i=CHARINDEX(@splitChar,@toSplitString)
WHILE @i>0
BEGIN
INSERT @tb VALUES(LEFT(@toSplitString,@i-1))
SET @toSplitString=RIGHT(@toSplitString,LEN(@toSplitString)-@i)
SET @i=CHARINDEX(@splitChar,@toSplitString)
END
IF LEN(@toSplitString)>0
INSERT @tb VALUES(@toSplitString)
RETURN
END
GO
然后我們稍微修改一下存儲過程：
復制代碼 代碼如下:
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author: jianxin160
-- Create date: 2010.11.05
-- Description: 統計商品
-- =============================================
ALTER PROCEDURE StatProductInfo
(
@ids VARCHAR(8000)
)
AS
BEGIN
DECLARE @followingTen INT
DECLARE @elevenToTwenty INT
DECLARE @twentyOneToThirty INT
DECLARE @thirtyOneToFourty INT
DECLARE @fourtyOneToFifty INT
DECLARE @fiftyOrMore INT
SELECT @followingTen=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(SELECT sp FROM dbo.GetSplitFieldsByString(@ids,',')) AND UnitPrice<10
SELECT @elevenToTwenty=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(SELECT sp FROM dbo.GetSplitFieldsByString(@ids,',')) AND UnitPrice BETWEEN 11 AND 20
SELECT @twentyOneToThirty=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(SELECT sp FROM dbo.GetSplitFieldsByString(@ids,',')) AND UnitPrice BETWEEN 21 AND 30
SELECT @thirtyOneToFourty=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(SELECT sp FROM dbo.GetSplitFieldsByString(@ids,',')) AND UnitPrice BETWEEN 31 AND 40
SELECT @fourtyOneToFifty=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(SELECT sp FROM dbo.GetSplitFieldsByString(@ids,',')) AND UnitPrice BETWEEN 41 AND 50
SELECT @fiftyOrMore=COUNT(*)
FROM dbo.Products
WHERE ProductID IN(SELECT sp FROM dbo.GetSplitFieldsByString(@ids,',')) AND UnitPrice>50
SELECT @followingTen AS '<$10',@elevenToTwenty AS '$11-$20',@twentyOneToThirty AS '$21-$30',
@thirtyOneToFourty AS '$31-$40',@fourtyOneToFifty AS '$41-$50',@fiftyOrMore AS '>$50'
END
GO
這樣通過執行EXEC dbo . StatProductInfo '3,4,8,10,22' 就可以得到想要的結果了：
試試這樣會不會快一些
復制代碼 代碼如下:
SELECT SUM(CASE WHEN UnitPrice < 10 THEN 1 ELSE 0 END) '<$10',
SUM(CASE WHEN UnitPrice BETWEEN 11 AND 20 THEN 1 ELSE 0 END) '$11-$20',
SUM(CASE WHEN UnitPrice BETWEEN 21 AND 30 THEN 1 ELSE 0 END) '$21-$30',
...
SUM(CASE WHEN UnitPrice > 50 THEN 1 ELSE 0 END) '>$10'
FROM dbo.Products
WHERE ProductID IN(SELECT sp FROM dbo.GetSplitFieldsByString(@ids,','))
