练习：Ado.Net 数据库增删改查--面向对象操作

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

namespace ConsoleApplication1
{
    //实体类 (封装字段、属性)
    public class Nation
    {
        private string code;

        public string Code
        {
            get { return code; }
            set { code = value; }
        }

        private string name;

        public string Name
        {
            get { return name; }
            set { name = value; }
        }
    }
}

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

namespace ConsoleApplication1
{
    //数据连接类：提供数据连接对象
    public class DataConnection
    {
        private static string connstr = "server=.; database=mydb; user=sa; pwd=ray;";
              
        public static SqlConnection Conn
        {
            get { return new SqlConnection(connstr);}
        }
    }
}

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

namespace ConsoleApplication1
{
    //数据访问类（实现增删改查操作）
    class NationData
    {
        private SqlConnection _conn; //连接对象
        private SqlCommand _cmd;    //命令对象
        private SqlDataReader _dr;  //读取器对象

        //构造方法，初始化成员（连接对象、命令对象）
        public NationData()
        {
            _conn = DataConnection.Conn; //对连接对象进行初始化
            _cmd = _conn.CreateCommand(); //对命令对象进行初始化 
        }

        /// <summary>
        /// 添加数据方法
        /// </summary>
        /// <param name="code">编号</param>
        /// <param name="name">名称</param>
        /// <returns>bool</returns>
        public bool Add(string code, string name)
        {
            _cmd.CommandText = "insert into Nation values(@code,@name)";
            _cmd.Parameters.Clear();
            _cmd.Parameters.AddWithValue("@code", code);
            _cmd.Parameters.AddWithValue("@name", name);

            _conn.Open();
            int n = _cmd.ExecuteNonQuery();
            _conn.Close();

            if (n > 0)
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        /// <summary>
        /// 查询所有数据方法
        /// </summary>
        /// <returns>List<T></returns>
        public List<Nation> Select()
        {
            _cmd.CommandText = "select *from Nation";
            _conn.Open();
            _dr = _cmd.ExecuteReader();

            //定义一个空的集合
            List<Nation> list=new List<Nation>();

            if (_dr.HasRows)
            {
                while (_dr.Read())
                {
                    //造一个Nation对象
                    Nation data = new Nation();
                    data.Code = _dr["Code"].ToString();
                    data.Name = _dr["Name"].ToString();

                    //扔到集合中
                    list.Add(data);
                }
            }
            _conn.Close();
            return list;
        }

        /// <summary>
        /// 根据条件查询方法
        /// </summary>
        /// <param name="code">编号</param>
        /// <returns>List<T></returns>
        public List<Nation> Select(string code)
        {
            _cmd.CommandText = "select *from Nation where Code=@code";
            _cmd.Parameters.Clear();
            _cmd.Parameters.AddWithValue("@code",code);
            _conn.Open();
            _dr = _cmd.ExecuteReader();


            //定义一个空的集合
            List<Nation> list = new List<Nation>();

            if (_dr.HasRows)
            {
                while (_dr.Read())
                {
                    //造一个Nation对象
                    Nation data = new Nation();
                    data.Code = _dr["Code"].ToString();
                    data.Name = _dr["Name"].ToString();

                    //扔到集合中
                    list.Add(data);
                }
            }
            _conn.Close();
            return list;
        }

        /// <summary>
        /// 删除数据方法
        /// </summary>
        /// <param name="code">编号</param>
        /// <returns>bool</returns>
        public bool Delete(string code)
        {
            _cmd.CommandText = "delete from Nation where Code=@code";
            _cmd.Parameters.Clear();
            _cmd.Parameters.AddWithValue("@code",code);

            _conn.Open();
            int n=_cmd.ExecuteNonQuery();
            _conn.Close();

            if ( n> 0)
            {
                return true;
            }
            else { return false; }
        }

        /// <summary>
        /// 修改数据方法
        /// </summary>
        /// <param name="code">编号</param>
        /// <param name="name">名称</param>
        /// <returns>bool</returns>
        public bool Update(string code,string name)
        {
            _cmd.CommandText = "update Nation set Name=@name where Code=@code";
            _cmd.Parameters.Clear();
            _cmd.Parameters.AddWithValue("@code",code);
            _cmd.Parameters.AddWithValue("@name",name);

            _conn.Open();
            int n = _cmd.ExecuteNonQuery();
            _conn.Close();

            if (n > 0)
            {
                return true;
            }
            else { return false; }
      
        }
    }
}

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            NationData data = new NationData();
            while (true)
            {
                Console.WriteLine("请输入要对数据进行的操作（1：添加、2：修改、3：删除、4：查询）：");
                string Operation = Convert.ToString(Console.ReadLine());
                if (Operation == "1")
                {
                    #region 添加数据
                    Console.Write("请输入要添加的编号：");
                    string code = Console.ReadLine();
                    Console.Write("请输入要添加的名称：");
                    string name = Console.ReadLine();

                    if (data.Add(code, name))
                    {
                        Console.WriteLine("添加成功，请按任意键刷新数据");
                        Console.ReadKey();
                        Console.Clear();

                        Console.WriteLine("=============刷新数据==============");
                        List<Nation> listSelect = data.Select();
                        foreach (Nation dataSelect in listSelect)
                        {
                            Console.WriteLine(dataSelect.Code + "	" + dataSelect.Name);
                        }
                    }
                    else
                    {
                        Console.WriteLine("添加失败");
                    }
                    Console.ReadKey();
                    #endregion

                    break;
                }
                if (Operation == "2")
                {
                    #region 修改数据
                    Console.Write("请输入要修改的编号：");
                    String codeUpdate = Console.ReadLine();
                    Console.Write("请输入修改后的名称：");
                    string nameUpdate = Console.ReadLine();

                    if (data.Update(codeUpdate, nameUpdate))
                    {
                        Console.WriteLine("修改成功，请按任意键刷新数据");
                        Console.ReadKey();
                        Console.Clear();

                        Console.WriteLine("==============刷新数据=============");
                        List<Nation> listSelect = data.Select();
                        foreach (Nation dataSelect in listSelect)
                        {
                            Console.WriteLine(dataSelect.Code + "	" + dataSelect.Name);
                        }
                    }
                    else { Console.WriteLine("修改失败"); }
                    Console.ReadKey();
                    #endregion

                    break;
                }
                if (Operation == "3")
                {
                    #region 删除数据
                    Console.WriteLine("请输入要删除数据的编号：");
                    string codeDelete = Console.ReadLine();

                    List<Nation> list = data.Select(codeDelete);
                    Console.WriteLine("这是你要删除的数据：");
                    foreach (Nation data1 in list)
                    {
                        Console.WriteLine(data1.Code + "	" + data1.Name);
                    }
                    Console.WriteLine("确认删除这条数据么？（Y/N）");
                    string s = Console.ReadLine();
                    if (s == "Y")
                    {
                        if (data.Delete(codeDelete))
                        {
                            Console.WriteLine("删除成功，按任意键刷新数据");
                            Console.ReadKey();
                            Console.Clear();

                            Console.WriteLine("=============刷新数据==============");
                            List<Nation> listSelect = data.Select();
                            foreach (Nation dataSelect in listSelect)
                            {
                                Console.WriteLine(dataSelect.Code + "	" + dataSelect.Name);
                            }
                        }
                        else { Console.WriteLine("删除失败"); }
                    }
                    else { Console.WriteLine("数据保留"); }
                    Console.ReadKey();
                    #endregion

                    break;
                }

                if (Operation == "4")
                {
                    #region 条件查询数据
                    Console.Write("请输入要查询的编号：");
                    string code = Console.ReadLine();
                    List<Nation> list = data.Select(code);
                    foreach (Nation datass in list)
                    {
                        Console.WriteLine(datass.Code+"	"+datass.Name);
                    }
                    Console.ReadKey();
                    #endregion

                    break;
                }
                else { Console.WriteLine("输入有误"); }
            }
        }
    }
}