要求

实现增删改查功能

制作代码展示

启动方法

  public void start(){Console.WriteLine("程序启动了，这是start方法");//判断是否登录成功if (login()){Console.WriteLine("登录成功!");Menu();//显示菜单}else{Console.WriteLine("账号或密码错误");}Console.ReadKey();}

登录功能方法

 public bool login(){bool reaf=false;Console.WriteLine("登陆功能,被调用的login方法");// 接收键盘输入，用户名，密码Console.WriteLine("请输入用户名：");usr_name = Console.ReadLine();Console.WriteLine("请输入密码：");string pwd = Console.ReadLine();// 去数据表中查询（需要用户表，用户名列，密码列）string sql = "select COUNT(*) from QQUser where QQID=" + usr_name + " and PassWord='" + pwd + "';";SqlCommand cmd = new SqlCommand(sql, connection);connection.Open();string a = cmd.ExecuteScalar().ToString();Console.WriteLine(a);connection.Close();if (a.Equals("1")){reaf = true;}else{reaf = false;}// 如果查询成功，代表登陆成功，给一个返回值// 如果查询不成功，登陆失败，给一个返回值return reaf;}

显示菜单方法

public void Menu()
{Console.WriteLine("1.查询好友");Console.WriteLine("2.删除好友");Console.WriteLine("3.添加好友");Console.WriteLine("4.修改好友");Console.WriteLine("q.退出");Console.WriteLine("请选择你要操作的选择");string a= Console.ReadLine();switch (a) { case "1":select_from();//查询方法break;case "2":break;case "3":break;case "4":break;default:break;}
}public void select_from() {string sql = "select * from BaseInfo where qqid=" + usr_name + ";";string sql2 = "select count(*) from BaseInfo where qqid=" + usr_name + ";";connection.Open();SqlCommand cmd2 = new SqlCommand(sql2, connection);int a = Convert.ToInt32(cmd2.ExecuteScalar().ToString());if (a > 0){SqlCommand cmd = new SqlCommand(sql, connection);SqlDataReader sdr = cmd.ExecuteReader();while (sdr.Read()){Console.WriteLine("QQ号：" + sdr["qqid"]);Console.WriteLine("昵称：" + sdr["nickname"]);Console.WriteLine("年龄：" + sdr["age"]);}}else{Console.WriteLine("你没有好友");}connection.Close();}