C#调用带输出参数的mysql存储过程

sq.conn.Open();
MySql.Data.MySqlClient.MySqlCommand mycmd = new MySql.Data.MySqlClient.MySqlCommand();
mycmd.CommandType = CommandType.StoredProcedure;
mycmd.Connection = sq.conn;
mycmd.CommandText = "sp_agent_otherSample_Payorder";

mycmd.Parameters.AddWithValue("_tysn", sTYSN);
MySql.Data.MySqlClient.MySqlParameter parout = new MySql.Data.MySqlClient.MySqlParameter("_re", MySql.Data.MySqlClient.MySqlDbType.VarChar);
parout.Direction = ParameterDirection.Output;
mycmd.Parameters.Add(parout);

mycmd.ExecuteNonQuery();
string sRe = "";
sRe = parout.Value.ToString();

sq.conn.Close();