请大虾解释一下SQLSERVER中存储过程的输出参数的作用

可以理解为c#里面的引用类型，传输的是地址...

CREATE PROC P_TEST

@Name VARCHAR(20),

@Rowcount INT OUTPUT

AS

BEGIN

SELECT * FROM T_Customer WHERE NAME=@Name

SET @Rowcount=@@ROWCOUNT

END

GO

----------------------------------------------------------------------------------------

--存储过程调用如下:

----------------------------------------------------------------------------------------

DECLARE @i INT

EXEC P_TEST 'A',@i OUTPUT

SELECT @i

--结果

/*

Name       Address    Tel                  

---------- ---------- -------------------- 

A          Address    Telphone 

（所影响的行数为 1 行）



            

----------- 

1



（所影响的行数为 1 行）

*/

----------------------------------------------------------------------------------------

--DotNet 部分(C#)

--WebConfig 文件:

----------------------------------------------------------------------------------------

......

</system.web>



   <!-- 数据库连接字符串

   -->

<appSettings>

      <add key="ConnectString" value="server=(local);User ID=sa;Password=;database=Test" />

</appSettings>

   

</configuration>

----------------------------------------------------------------------------------------

--C#代码:(用到两个测试控件,DataGrid1(用于显示绑定结果集合),Lable(用于显示存储过程返回单值)

----------------------------------------------------------------------------------------

//添加数据库引用

using System.Data.SqlClient;

......

private void Page_Load(object sender, System.EventArgs e)

   {

    // 在此处放置用户代码以初始化页面

    String DBConnStr;

    DataSet MyDataSet=new DataSet();

    System.Data.SqlClient.SqlDataAdapter DataAdapter=new System.Data.SqlClient.SqlDataAdapter();

    DBConnStr=System.Configuration.ConfigurationSettings.AppSettings["ConnectString"];

    System.Data.SqlClient.SqlConnection myConnection = new System.Data.SqlClient.SqlConnection(DBConnStr);

    if (myConnection.State!=ConnectionState.Open) 

    {

     myConnection.Open();

    }   

    System.Data.SqlClient.SqlCommand myCommand = new System.Data.SqlClient.SqlCommand("P_Test",myConnection);

    myCommand.CommandType=CommandType.StoredProcedure;

    //添加输入查询参数、赋予值

    myCommand.Parameters.Add("@Name",SqlDbType.VarChar);

    myCommand.Parameters["@Name"].Value ="A";



    //添加输出参数

    myCommand.Parameters.Add("@Rowcount",SqlDbType.Int);

    myCommand.Parameters["@Rowcount"].Direction=ParameterDirection.Output;





    myCommand.ExecuteNonQuery();

    DataAdapter.SelectCommand = myCommand;



    if (MyDataSet!=null)

    {

      DataAdapter.Fill(MyDataSet,"table");

    }

   

    DataGrid1.DataSource=MyDataSet;

    DataGrid1.DataBind();

    //得到存储过程输出参数

    Label1.Text=myCommand.Parameters["@Rowcount"].Value.ToString();



    if (myConnection.State == ConnectionState.Open)

    {

     myConnection.Close();

    }



   }

USE AdventureWorks;

GO

IF OBJECT_ID ( 'Production.uspGetList', 'P' ) IS NOT NULL 

    DROP PROCEDURE Production.uspGetList;

GO

CREATE PROCEDURE Production.uspGetList @Product varchar(40) 

    , @MaxPrice money 

    , @ComparePrice money OUTPUT

    , @ListPrice money OUT

AS

    SELECT p.[Name] AS Product, p.ListPrice AS 'List Price'

    FROM Production.Product AS p

    JOIN Production.ProductSubcategory AS s 

      ON p.ProductSubcategoryID = s.ProductSubcategoryID

    WHERE s.[Name] LIKE @Product AND p.ListPrice < @MaxPrice;

-- Populate the output variable @ListPprice.

SET @ListPrice = (SELECT MAX(p.ListPrice)

        FROM Production.Product AS p

        JOIN  Production.ProductSubcategory AS s 

          ON p.ProductSubcategoryID = s.ProductSubcategoryID

        WHERE s.[Name] LIKE @Product AND p.ListPrice < @MaxPrice);

-- Populate the output variable @compareprice.

SET @ComparePrice = @MaxPrice;

GO