using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace 实体类_数据访问类.App_Code{    public class Users    {        private string _username;        //封装        /// <summary>        /// 用户名        /// </summary>        public string username        {            get { return _username; }            set { _username = value; }        }        private string _password;        /// <summary>        /// 密码        /// </summary>        public string password        {            get { return _password; }            set { _password = value; }        }        private string _nickname;        /// <summary>        /// 昵称        /// </summary>        public string nickname        {            get { return _nickname; }            set { _nickname = value; }        }        private bool _sex;        /// <summary>        /// 性别        /// </summary>        public bool sex        {            get { return _sex; }            set { _sex = value; }        }        //属性扩展，可以再添加一个方法，把性别转换成字符串类型，打印时直接u.sex1，不用再在program里面每次单独转换        public string sex1        {            get { return (_sex ? "男" : "女"); }//只读取，不能填写或改写        }        private DateTime _brithday;        /// <summary>        /// 生日        /// </summary>        public DateTime brithday        {            get { return _brithday; }            set { _brithday = value; }        }        //属性扩展        public string brithday1        {            get { return _brithday.ToString("yyyy年MM月dd日");}        }        private string _nation;        /// <summary>        /// 民族        /// </summary>        public string nation        {            get { return _nation; }            set { _nation = value; }        }        //属性扩展        public string nationname        {            get             {                NationData ndata = new NationData();                string end = ndata.select(_nation);                return end;            }        }    }}复制代码复制代码using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Data.SqlClient;namespace 实体类_数据访问类.App_Code{    public class UsersData    {         //调用数据连接类、数据操作类        SqlConnection conn = null;//等于null，不占空间        SqlCommand cmd = null;        //构造函数        public UsersData()//构造函数名称与类名一致        {            conn = new SqlConnection("server=.;database=Data0720;user=sa;pwd=123;");            cmd = conn.CreateCommand();        }        //添加        /// <summary>        /// Users表添加方法        /// </summary>        /// <param name="u">要添加到数据库中的Users对象</param>        public void Insert(Users u)//有实体类，括号内的参数把实体类的对象放进去        {            cmd.CommandText = "insert into Users values(@a,@b,@c,@d,@e,@f)";            cmd.Parameters.Clear();//一定要先清空            cmd.Parameters.Add("@a", u.username);            cmd.Parameters.Add("@b", u.password);            cmd.Parameters.Add("@c", u.nickname);            cmd.Parameters.Add("@d", u.sex);            cmd.Parameters.Add("@e", u.brithday);            cmd.Parameters.Add("@f", u.nation);            conn.Open();            cmd.ExecuteNonQuery();            conn.Close();        }        //查询（一条信息）        /// <summary>        /// Users表查询方法        /// </summary>        /// <param name="Uname">查询数据库中的Users信息表</param>        /// <returns></returns>        public Users select(string Uname)        {            Users u = null;            //查            cmd.CommandText = "select * from Users where username=@a";            cmd.Parameters.Clear();            cmd.Parameters.Add("@a",Uname);            conn.Open();            SqlDataReader dr = cmd.ExecuteReader();            if (dr.HasRows)            {                dr.Read();                u = new Users();                u.username = dr["username"].ToString();                u.password = dr["password"].ToString();                u.nickname = dr["nickname"].ToString();                u.sex = Convert.ToBoolean(dr["sex"]);                u.brithday = Convert.ToDateTime(dr["brithday"]);                u.nation = dr["nation"].ToString();            }            conn.Close();            return u;        }        //删除        /// <summary>        /// Users表删除方法        /// </summary>        /// <param name="Uname">删除数据库中的Users信息表中的信息</param>        public bool Delete(string Uname)        {            bool delok = false;            cmd.CommandText = "delete from Users where username=@a";            cmd.Parameters.Clear();            cmd.Parameters.Add("@a",Uname);                        conn.Open();            try//验证、判断是否删除成功，有可能是数据库服务没开，服务器连接不上，这样不可以返回删除成功            {                cmd.ExecuteNonQuery();//如果没执行成功，程序报错，用try包起来                delok = true;            }            catch { }//让catch捕获住错误，不让程序崩溃，执行delok = false;，这个是一开始设置的默认的，所以catch可以空着            //finally//必须走，            //{                conn.Close();//这一步必须走，finally可写可不写            //}            return delok;        }        //修改        /// <summary>        /// Users表修改方法        /// </summary>        /// <param name="u">修改数据库中的Users信息表中的信息</param>        public void Update(Users u3)             {            cmd.CommandText = "update Users set [password]=@b,sex=@d where username =@a";            cmd.Parameters.Clear();            cmd.Parameters.Add("@b",u3.password);            cmd.Parameters.Add("@d",((u3.sex==true)?"1":"0"));            cmd.Parameters.Add("@a",u3.username);            conn.Open();            cmd.ExecuteNonQuery();            conn.Close();        }                //查询所有信息        public List<Users> select()//用泛型集合，不规定个数，单数固定类型都得是Users类型,放置所有Users数据对象        {            List<Users> list = new List<Users>();            cmd.CommandText = "select * from Users";            conn.Open();            SqlDataReader dr = cmd.ExecuteReader();            if (dr.HasRows)//如果数据表中有数据            {                while (dr.Read())//循环读取全部数据                {                    //每读取一行数据，就只做一个Users对象                    Users u = new Users();                    u.username = dr["username"].ToString();                    u.password = dr["password"].ToString();                    u.nickname = dr["nickname"].ToString();                    u.sex = Convert.ToBoolean(dr["sex"]);                    u.brithday = Convert.ToDateTime(dr["brithday"]);                    u.nation = dr["nation"].ToString();                    //在循环中，把制作好的每一个对象都放到集合中去                    list.Add(u);                }            }            conn.Close();            return list;        }    }}复制代码复制代码using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace 实体类_数据访问类.App_Code{    public class Nation    {        private string _nationcode;        public string nationcode        {            get { return _nationcode; }            set { _nationcode = value; }        }        private string _nationname;        public string nationname        {            get { return _nationname; }            set { _nationname = value; }        }        }}复制代码复制代码using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Data.SqlClient;namespace 实体类_数据访问类.App_Code{    public class NationData    {        SqlConnection conn = null;        SqlCommand cmd = null;        public NationData()        {            conn = new SqlConnection("server=.;database=Data0720;user=sa;pwd=123;");            cmd = conn.CreateCommand();        }        public string select(string code)        {            string end = "<无>";            cmd.CommandText = "select * from Nation where nationcode=@a";            cmd.Parameters.Clear();            cmd.Parameters.Add("@a",code);            conn.Open();            SqlDataReader dr = cmd.ExecuteReader();            if (dr.HasRows)//如果有数据            {                dr.Read();                end = dr["nationname"].ToString();            }            else            {                                     }            conn.Close();            return end;        }    }}复制代码复制代码using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;using 实体类_数据访问类.App_Code;using System.Data.SqlClient;namespace 实体类_数据访问类{    class Program    {        static void Main(string[] args)        {            //打印出所有信息            while (true)            {                Console.Clear();//清屏                Console.WriteLine("======================人员信息表======================");                Console.WriteLine();                Console.WriteLine("用户名" + "\t" + "密码" + "\t" + "昵称" + "\t" + "性别" + "\t" + "生日" + "            " + "民族");                //实例化,先引用空间名                SqlConnection conn = new SqlConnection("server=.;database=Data0720;user=sa;pwd=123");                //设置数据库中的表的操作                SqlCommand cmd = conn.CreateCommand();                cmd.CommandText = "select * from Users";                //执行操作                conn.Open();                SqlDataReader dr = cmd.ExecuteReader();                while (dr.Read())                {                    Console.WriteLine(dr["username"] + "\t" + dr["password"] + "\t" + dr["nickname"] + "\t" + (((bool)dr["sex"]) ? "男" : "女") + "\t" + Convert.ToDateTime(dr["brithday"]).ToString("yyyy年MM月dd日") + "\t" + dr["nation"]);                }                conn.Close();                Console.WriteLine("-------------------------------------------------------------");                Console.Write("请输入您想执行的操作（1.添加 2.删除 3.修改 4.查询某条信息 5.查询全部信息）:");                string n = Console.ReadLine();                                //实例化                UsersData udata = http://www.mamicode.com/new UsersData();//在这个类被实例化的时候UsersData()代表的就是UsersData类中的构造函数                if (n == "1")                {                    //添加                    #region                    //实例化                    Users u = new Users();//构造函数是默认的，可以不写，在这个类被实例化的时候Users()代表的就是构造函数                    Console.Write("请输入用户名：");                    u.username = Console.ReadLine();                    Console.Write("请输入密码：");                    u.password = Console.ReadLine();                    Console.Write("请输入昵称：");                    u.nickname = Console.ReadLine();                    Console.Write("请输入性别：");                    u.sex = (Console.ReadLine() == "男");                    Console.Write("请输入生日：");                    u.brithday = Convert.ToDateTime(Console.ReadLine());                    Console.Write("请输入民族：");                    u.nation = Console.ReadLine();                    //实例化  UsersData                    udata.Insert(u);//调用udata里面的Insert()方法                    #endregion                }                else if (n == "2")                {                    //删除                    #region                    Console.Write("请输入要删除的用户名：");                    string Uname = Console.ReadLine();                    Users u2 = udata.select(Uname);                    if (u2 != null)                    {                        Console.WriteLine("已查到此用户，请执行删除！");                        Console.ReadLine();                        bool ok = udata.Delete(Uname);                        if (ok)                        {                            Console.WriteLine("删除成功！");                        }                        else                        {                            Console.WriteLine("删除失败！");                        }                    }                    else                    {                        Console.WriteLine("请核实用户名输入是否正确！");                    }                    #endregion                }                else if (n == "3")                {                    //修改                    #region                    Users u3 = new Users();                    Console.Write("请输入您要修改的用户名：");                    u3.username = Console.ReadLine();                    if (u3 != null)                    {                        Console.Write("已查到此用户，请进行修改！");                        Console.ReadLine();                        Console.Write("请输入修改后的密码：");                        u3.password = Console.ReadLine();                        Console.Write("请输入修改后的性别：");                        u3.sex = (Console.ReadLine() == "男");                        udata.Update(u3);                    }                    else                    {                        Console.WriteLine("未查到您输入的用户名，请核实后重新输入！");                    }                    #endregion                }                else if (n == "4")                {                    //查一条数据                     #region                    Console.Write("请输入你要查找的用户名：");                    string Uname = Console.ReadLine();                    Users u = new UsersData().select(Uname);                    if (u != null)                    {                        Console.WriteLine("已查到此用户！");                        Console.ReadLine();                        Console.WriteLine("用户名" + "\t" + "密码" + "\t" + "昵称" + "\t" + "性别" + "\t" + "生日" + "            " + "民族");                        Console.Write(u.username + "\t" + u.password + "\t" + u.nickname + "\t" + u.sex + "\t" + u.brithday + "\t" + u.nation);                        Console.ReadLine();                    }                    else                    {                        Console.WriteLine("未查到此用户信息，请核实后重新输入！");                    }                    #endregion                }                else if (n == "5")                {                    List<Users> ulist = new UsersData().select();                    if (ulist.Count > 0)//如果有数据                    {                        Console.WriteLine("用户名" + "\t" + "密码" + "\t" + "昵称" + "\t" + "性别" + "\t" + "生日" + "             " + "民族");                        //循环打印，用foreach                        foreach (Users u in ulist)//遍历，把每一个数据都拿出来看一下                        {                            Console.WriteLine(u.username + "\t" + u.password + "\t" + u.nickname + "\t" + u.sex1 + "\t" + u.brithday1 + "\t" + u.nationname);                        }                        Console.ReadLine();                    }                    }                else                {                    Console.WriteLine("您的输入有误，请重新输入！");                }            }            Console.ReadLine();        }    }}