[转载]不固定参数的存储过程

baacloud免费翻墙vpn注册使用

[转载]不固定参数的存储过程 – KenshinCui’s Blog – 博客园.

我们知道存储过程是不支持不固定参数情况的(包括数组参数),可是有时候我们的参数又必须是不固定的,怎么办呢?我想此时不妨使用字符串参数来帮助我们解决这种情况,利用字符串分割的方法将一个参数分割成数个参数来解决。下面我们看一个例子:

假设现在给你一个产品信息列表(显示出各个商品的基本信息),现在我想要根据所选择商品进行统计(任意选择几种),例如统计出价 格<10,11-20,21-30,31-40,41-50,50以上的商品个有多少个(姑且认为就统计这些)。此时如果使用存储过程就势必需要传 入所选商品的id作为参数,但是id个数是不固定的。此时估计会有人这样写:

代码

SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author: jianxin160 -- Create date: 2010.11.05 -- Description: 统计商品 -- ============================================= 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

其实如果你测试一下(例如:EXEC dbo . StatProductInfo ‘3,4,8,10,22’ )是有问题的,SQL server认为这整个是一个参数,转换时出错。此时我们想一下如果这些字段在一个虚表中就容易操作多了,但是一般虚表是有其他表通过查询得到,现在根本 无法查询又哪来的虚表呢?聪明的朋友或许已经想到可以使用”表值函数”。对,答案就是使用”表值函数”。我们知道”表值函数”可以返回一个”Table” 类型的变量(相当于一张虚表,存放于内存中),我们首先将字符串分割存放到”表值函数”的一个字段中,然后我们再从”表值函数”中查询就可以了(这个例子 也是”表值函数”的一个典型应用)。具体SQL如下:

代码

SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author: cmj -- Create date: 2010.11.05 -- Description: 返回一个Table,只有一列,每一行的数据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

然后我们稍微修改一下存储过程:

代码

SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author: jianxin160 -- Create date: 2010.11.05 -- Description: 统计商品 -- ============================================= 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

这样通过执行EXEC dbo . StatProductInfo ‘3,4,8,10,22’ 就可以得到想要的结果了:

赞(0) 打赏
分享到: 更多 (0)

觉得文章有用就打赏一下文章作者

支付宝扫一扫打赏

微信扫一扫打赏