如何从C#函数的存储过程返回多个输出参数

Question

我正在使用输出参数从我的数据库中获取值.

这是我的存储过程:

ALTER PROCEDURE [dbo].[sp_GetCustomerMainData] 
    -- Add the parameters for the stored procedure here
        @Reference nvarchar(100),
        @SubscriptionPIN nvarchar(100) OUTPUT,
        @SignupDate nvarchar(100) OUTPUT,
        @ProductCount int OUTPUT
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    SET @SubscriptionPIN = 'N/A'
    SET @SignupDate = 'N/A'
    SET @ProductCount = 0

    -- Insert statements for procedure here
    IF EXISTS(SELECT [SubscriptionPIN] FROM [Norton].[dbo].[Customers] WHERE [Reference] = @Reference)
    BEGIN
        SELECT TOP 1 @SubscriptionPIN = [SubscriptionPIN], @SignupDate = SignUpDate  FROM [Norton].[dbo].[ProductList] WHERE [Reference] = @Reference
        SET @ProductCount = (SELECT COUNT(*) FROM [Norton].[dbo].[ProductList] WHERE [Reference] = @Reference)
    END

    RETURN (@SubscriptionPIN)
    RETURN (@SignupDate)
    RETURN (@ProductCount)
END

我不确定最后的回报:

RETURN (@SubscriptionPIN)
RETURN (@SignupDate)
RETURN (@ProductCount)

另一方面,这是c#代码:

using (SqlConnection con = new SqlConnection(connectionInfo))
{
    using (SqlCommand cmd = new SqlCommand("sp_GetCustomerMainData", con) { CommandType = CommandType.StoredProcedure })
    {
        cmd.Parameters.Add("@Reference", SqlDbType.NVarChar).Value = CustomerReferenceID;

        SqlParameter SubscriptionPIN = new SqlParameter("@TheCustomerID", SqlDbType.NVarChar) { Direction = ParameterDirection.Output };
        cmd.Parameters.Add(SubscriptionPIN);

        SqlParameter SignupDate = new SqlParameter("@SignupDate", SqlDbType.NVarChar) { Direction = ParameterDirection.Output };
        cmd.Parameters.Add(SignupDate);

        SqlParameter ProductCount = new SqlParameter("@ProductCount", SqlDbType.Int) { Direction = ParameterDirection.Output };
        cmd.Parameters.Add(ProductCount);

        con.Open();

        try
        {
            cmd.ExecuteNonQuery();

            if (cmd.Parameters["@TheCustomerID"].Value.ToString() != "N/A")
            {
                aStatus.SubscriptionPIN = cmd.Parameters["@TheCustomerID"].Value.ToString();
                aStatus.SignupDate = cmd.Parameters["@SignupDate"].Value.ToString();
                aStatus.ProductCount = int.Parse(cmd.Parameters["@ProductCount"].Value.ToString());
                aStatus.Result = "0: Reference ID Found";
             }
             else
             {
                 aStatus.Result = "1: Reference ID does not exists";
                 return aStatus;
             }
          }
          catch (SqlException sqlExc)
          {
              foreach (SqlError error in sqlExc.Errors)
              {
                  aStatus.Result = string.Format("{0}: {1}", error.Number, error.Message);
                  return aStatus;
              }
          }
      }
}

当我运行此代码时,我收到错误:

System.InvalidOperationException:String [1]: 在System.Data.SqlClient.SqlCommand.SetUpRPCParameters(_SqlRPC rpc,
System.SataClient)的System.Data.SqlClient.SqlParameter.Validate(Int32 index,Boolean isCommandProc)中
,Size属性的大小为0 . System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior,RunBehavior runBehavior,Boolean returnStream,Boolean )
中的System.Data.SqlClient.SqlCommand.BuildRPC(布尔inSchema,SqlParameterCollection参数,_SqlRPC和rpc)
中的Int32 startCount,Boolean inSchema,SqlParameterCollection参数)系统
中的System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior,RunBehavior runBehavior,Boolean returnStream,String方法,DbAsyncResult结果)
处于系统的System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult结果,String methodName,Boolean sendToPipe)
中的async).Data.SqlClient.SqlCommand.ExecuteNonQuery()

我不知道从存储过程发送许多输出参数的正确方法是什么,有人可以帮忙吗？

Answer 1

您需要指定nvarchar参数的最大长度：

SqlParameter SubscriptionPIN = new SqlParameter("@TheCustomerID", SqlDbType.NVarChar, 100) { Direction = ParameterDirection.Output };
cmd.Parameters.Add(SubscriptionPIN);
SqlParameter SignupDate = new SqlParameter("@SignupDate", SqlDbType.NVarChar, 100) { Direction = ParameterDirection.Output };
cmd.Parameters.Add(SignupDate);

return从存储过程中删除语句。您无需执行任何操作即可返回输出参数。（此外，您只能使用一个return语句，并且只能返回整数值。您可以使用带有方向的参数ReturnValue来获取返回值。）