c# posgre 接続 select

using System;
using Npgsql;

namespace db01
{
    class Program
    {
        static void Main(string[] args){
            //接続文字列
            NpgsqlConnection conn = new NpgsqlConnection("Server=localhost;Port=5432;User ID=postgres;Database=postgres;Password=Chatdb01;Enlist=true");
            //PostgreSQLへ接続
            conn.Open();


            NpgsqlCommand cmd = new NpgsqlCommand("select version()", conn);
            var serverversion = (String)cmd.ExecuteScalar();

            Console.WriteLine("PostgreSQL server version: {0}", serverversion);
            conn.Close();
        }
    }
}