C# 调用存储过程 输出参数

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data;
using System.Data.SqlClient;

namespace CallSp2
{
    class CallSp2
    {
        static void Main(string[] args)
        {
            //创建数据库连接对象
            SqlConnection conn = new SqlConnection(@"Data Source=.;Initial Catalog=Northwind;Integrated Security=True");

            try
            {
                conn.Open();
                SqlCommand cmd = conn.CreateCommand();
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.CommandText = "sp_orders_by_employeeid2";

                //创建输入参数
                SqlParameter inparm = cmd.Parameters.Add("@employeeid", SqlDbType.Int);
                inparm.Direction = ParameterDirection.Input;
                inparm.Value = 2;

                //创建“输出”参数
                SqlParameter ouparm = cmd.Parameters.Add("@ordercount", SqlDbType.Int);
                ouparm.Direction = ParameterDirection.Output;//方向

                //create return value parameter
                SqlParameter retval = cmd.Parameters.Add("return_value", SqlDbType.Int);
                retval.Direction = ParameterDirection.ReturnValue;

                SqlDataReader rdr = cmd.ExecuteReader();

                while(rdr.Read())
                {
                    Console.WriteLine("{0} {1}", rdr[0].ToString().PadRight(5), rdr[1].ToString());
                }

                rdr.Close();

                //显示输出参数
                Console.WriteLine("The output parameter value is {0}", cmd.Parameters["@ordercount"].Value);

                Console.WriteLine("The return_value is {0}", cmd.Parameters["return_value"].Value);

            }
            catch (SqlException ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                conn.Close();
            }
        }
    }
}