命名管道提供程序，错误：40 c＃

Question

当我尝试从查询中获取结果作为列表时，我一直收到此错误。如果我尝试获得1个结果，我可以连接到数据库。

代码是：

string connectionString = "server=ip;uid=root;pwd=pass;database=database;";
string queryString = "SELECT pass_name FROM passStore";

List<string> tempList = new List<string>();

using (SqlConnection connection = new SqlConnection(connectionString))
        {
            SqlCommand command = new SqlCommand(queryString, connection);
            connection.Open();
            SqlDataReader reader = command.ExecuteReader();

            while (reader.Read())
            {
                if (!reader.IsDBNull(0))
                {
                    tempList.Add(reader[0].ToString() + " " + reader[1].ToString());
                }
            }
            reader.Close();
        }