操作数据库（增删改）

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

namespace ConsoleApplication1
{
    class Program4
    {
        static void Main4(string[] args)
        {
            //用户输入要删除的数据主键值
            Console.WriteLine("请输入要删除的代号：");
            string code = Console.ReadLine();

            //判断该数据存不存在
            SqlConnection conn = new SqlConnection("server=.;database=mydb;user=sa;pwd=123");
            SqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = "select * from Info where Code='"+code+"'";
            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader();
            

            if (dr.HasRows)
            {
                //说明该数据存在
                Console.WriteLine("查到该数据，是否要执行删除操作，如果要删除请输入：1");
                int sc = Convert.ToInt32(Console.ReadLine());

                if (sc == 1)
                {
                    //删除
                    dr.Close(); //关闭读取器

                    cmd.CommandText = "delete from Info where Code='"+code+"'";
                    cmd.ExecuteNonQuery();
                    Console.WriteLine("删除成功！");
                    
                }
                else
                {
                    //不删除
                    dr.Read();

                    string sex = Convert.ToBoolean(dr[2])?"男":"女";
                    string nation = MinZu(dr[3].ToString());

                    string str = "代号："+dr[0]+"	姓名："+dr[1]+"	性别："+sex+"	民族："+nation+"	生日："+dr[4];

                    Console.WriteLine(str);


                }
            }
            else
            {
                //数据不存在
                Console.WriteLine("输入的代号错误！");
            }

            conn.Close();
            Console.ReadLine();
        }


        static string MinZu(string code)
        {
            string name="";
            SqlConnection conn = new SqlConnection("server=.;database=mydb;user=sa;pwd=123");
            SqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = "select Name from Nation where Code = '" + code + "'";
            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader();
            if (dr.HasRows)
            {
                dr.Read();
                name = dr[0].ToString();
            }
            conn.Close();

            return name;
        }
    }
}

添加

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

namespace ConsoleApplication1
{
    class Program3
    {
        static void Main3(string[] args)
        {
            //让用户输入要添加的内容
            Console.WriteLine("请输入要添加的代号：");
            string code = Console.ReadLine();

            Console.WriteLine("请输入姓名：");
            string name = Console.ReadLine();

            Console.WriteLine("请输入性别：");
            bool sex = Console.ReadLine()=="男"?true:false;

            Console.WriteLine("请输入民族：");
            string nation = Console.ReadLine();

            Console.WriteLine("请输入生日：");
            string birthday = Console.ReadLine();

            string nationcode = "n001";

            //将民族名称转为名族代号
            SqlConnection conn = new SqlConnection("server=.;database=mydb;user=sa;pwd=123");
            SqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = "select Code from Nation where Name = '"+nation+"'";
            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader();
            if (dr.HasRows)
            {
                dr.Read();
                nationcode = dr[0].ToString();
            }
            conn.Close();

            //往Info表添加数据
            cmd.CommandText = "insert into Info values('"+code+"','"+name+"','"+sex+"','"+nationcode+"','"+birthday+"')";
            conn.Open();
            cmd.ExecuteNonQuery();
            conn.Close();
            Console.WriteLine("添加成功！");

            Console.ReadLine();
        }
    }
}