ADO SQL属性扩展————多表组合成新的更完整的表

create database guoji--建立数据库
go
use guoji
go
create table xinxi--建立表一
(
name varchar(20),
minzu varchar(20)
)
insert into xinxi values('lisi','');
insert into xinxi values('wangwu','');
insert into xinxi values('zhaoliu','');
select * from xinxi
go

create table minz--建立表二
(
mcode varchar(20),
mname varchar(20)
)
insert into minz values('','汉族');
insert into minz values('','满族');
insert into minz values('','藏族');
go
select *  from minz

要求：查询表一，民族部分用汉族展现出来！！！

//进行xinxi表的实体化
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace biao.App_Code
{
    public class xinxi
    {
        private string _name;
        public string name
        {
            get { return _name; }
            set { _name = value; }
        }

        private string _minzu;
        public string minzu//用这个接受数据
        {
            get { return _minzu; }
            set { _minzu = value; }
        }
        public string minzustr//用这个输出数据
        {
            get
            {
                minzdata n = new minzdata();
                string m = n.mname(_minzu);
                return m;
            }
        }

//进行xinxi表的数据数据访问类
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlClient;

namespace biao.App_Code
{
    public class xinxidata
    {
        SqlConnection cnn = null;
        SqlCommand cmd = null;
        public xinxidata()
        {
            cnn = new SqlConnection("server=.;database=guoji;user=sa;pwd=123");
            cmd = cnn.CreateCommand();
        }

        public List<xinxi> select()//查询全部信息，把信息放到集合里
        {
            xinxi x = null;
            List<xinxi> list = new List<xinxi>();
            cmd.CommandText = "select * from xinxi";
            cnn.Open();
            SqlDataReader ss = cmd.ExecuteReader();
            if (ss.HasRows)
            {

                while (ss.Read())
                {
                    x = new xinxi();
                    x.name = ss["name"].ToString();
                    x.minzu = ss["minzu"].ToString();
                    list.Add(x);
                }
            }
            else
            {
                Console.WriteLine("此表为空，没有数据！");
            }
            cnn.Close();
            return list;
        }

//minz表的实体化
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace biao.App_Code
{
    public class minz
    {
        private string _mcode;
        public string mcode
        {
            get { return _mcode; }
            set { _mcode = value; }
        }

        private string _mname;
        public string mname
        {
            get { return _mname; }
            set { _mname = value; }
        }

    }
}

//minz表的数据访问类
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlClient;

namespace biao.App_Code
{
    public class minzdata
    {
        SqlConnection cnn = null;
        SqlCommand cmd = null;
        public minzdata()
        {
            cnn = new SqlConnection("server=.;database=guoji;user=sa;pwd=123");
            cmd = cnn.CreateCommand();
        }

        public string mname(string code)//根据编号查姓名
        {

            string a = "<无>";
            cmd.CommandText = "select * from minz where mcode=@a";
            cmd.Parameters.Clear();
            cmd.Parameters.Add("@a",code);
            cnn.Open();
            SqlDataReader ss = cmd.ExecuteReader();
            if (ss.HasRows)//是否有这个数据
            {
                ss.Read();
                a = ss[].ToString();

            }
            else
            {
                Console.WriteLine("数据表为空");
            }

            cnn.Close();

            return a;
        }

    }
}

//在program类的主函数
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using biao.App_Code;

namespace biao
{
    class Program
    {
        static void Main(string[] args)
        {
            xinxidata a = new xinxidata();
            List<xinxi> list = a.select();
            foreach (xinxi b in list)//遍历集合查询全部内容
            {
                Console.WriteLine(b.name + "  " + b.minzustr);//用b.minzustr输出语句
            }

            Console.ReadLine();
        }
    }
}

完！！