C# 例子1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Com.Dys.Model
{
    class User
    {
        private int id;
        private string username;
        private string password;

        public int Id
        {
            get { return this.id; }
            set { this.id = value; }
        }

        public string Username
        {
            get { return this.username; }
            set { this.username = value; }
        }

        public string Password
        {
            get { return this.password; }
            set { this.password = value; }
        }

        public User()
        {
        }

        public User(int id, string username, string password)
        {
            this.id = id;
            this.username = username;
            this.password = password;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Com.Dys.Utils
{
    class DBUtils
    {
        public static SqlDataReader GetSQLDataReader(string Sql)
        {
            try
            {
                string SqlConnection = "server=127.0.0.1;database=dingyingsi;uid=sa;pwd=dys123;";
                //windows身份验证
                //string sqlconn = "server=(local);database=keede1228;integrated security=SSPI;";
                SqlConnection Connection = new SqlConnection(SqlConnection);
                Connection.Open();
                SqlCommand Command = new SqlCommand(Sql, Connection);
                SqlDataReader Reader = Command.ExecuteReader();
                return Reader;
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
                Console.ReadLine();
            }
            return null;
        }
    }
}

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Com.Dys.Model;
using Com.Dys.Utils;
using System.Data.SqlClient;

namespace Demo01
{
    class Demo
    {
        static void Main(string[] args)
        {
           string Sql = "select id, username, password from [user]";
           SqlDataReader Reader = DBUtils.GetSQLDataReader(Sql);
           IEnumerable Users = Encapsulate(Reader);
           foreach(User user in Users)
           {
               Console.WriteLine("id = {0}", user.Id);
               Console.WriteLine("username = {0}", user.Username);
               Console.WriteLine("password = {0}", user.Password);
           }
           Console.ReadLine();
        }

        static IEnumerable Encapsulate(SqlDataReader Reader)
        {
            ArrayList al = new ArrayList();
            User user = null;
            if (Reader == null)
            {
                return null;
            }

            while (Reader.Read())
            {
                user = new User();
                user.Id = (int)Reader["id"];
                user.Username = (string)Reader["username"];
                user.Password = (string)Reader["password"];

                al.Add(user);
            }
            return al;
        }
    }
}