c#调用带输出参数的存储过程

sql server中编写一个存储过程：

CREATE PROCEDURE ProGetPWD
   @username varchar(20),
   @password varchar(20) OUTPUT
AS
BEGIN
   SELECT @password = password
   FROM Users
   WHERE username = @username
END

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下面是.NET中调用存储过程的方法:

string strConnection = "user id=sa;password=sa;initial catalog=MyTest;Server=YHB;Connect Timeout=30";
            using (SqlConnection conn = new SqlConnection(strConnection))
            {
                conn.Open();
                using (SqlCommand sqlComm = conn.CreateCommand())
                {
                    //设置要调用的存储过程的名称
                    sqlComm.CommandText = "GetPWD";
                    //指定SqlCommand对象传给数据库的是存储过程的名称而不是sql语句
                    sqlComm.CommandType = CommandType.StoredProcedure;

                    SqlParameter username = sqlComm.Parameters.Add(new SqlParameter("@username", SqlDbType.VarChar, 20));
                    //指明"@username"是输入参数
                    username.Direction = ParameterDirection.Input;
                    //为“@username”参数赋值
                    username.Value = this.txt_username.Text;

                    SqlParameter password = sqlComm.Parameters.Add(new SqlParameter("@password", SqlDbType.VarChar, 20));
                    //指定"@password"为输出参数
                    password.Direction = ParameterDirection.Output;
                    //执行
                    sqlComm.ExecuteNonQuery();
                    //得到输出参数的值,把赋值给name,注意,这里得到的是object类型的,要进行相应的类型轮换
                    string passwrod = Convert.ToString(sqlComm.Parameters["@password"].Value);
                    MessageBox.Show(passwrod);
                }
            }