using System;

public static class Program {

    public static void Main() {

        DAL.DadosConexao.isServ = true;

        var con = DAL.DadosConexao.StringConexao;

    }

}

​

namespace DAL {

    public static class DadosConexao {

        public static string servidor { get; set; }

        public static bool isServ { get; set; }

​

        public static string StringConexao {

            get {

                if (!isServ) servidor = Environment.MachineName.ToString();

                return "Data Source=" + servidor + 

                       "\\MINHAINSTANCIA;" + 

                       "Initial Catalog=MINHABASE;" + 

                       "Persist Security Info=True;" + 

                       "User ID=sa;" + 

                       "Password=123456";

            }

        }

    }

}

​