一个系统，进入登入界面后跳出别的界面，那个登入界面怎么自动关掉？
  private void Lobt_Login_Click(object sender, EventArgs e)
        {
            SqlConnection con = MysqlConnection();            
            con.Open();
            String str = "select Uname ,Upass,Utype  from S_user where  Uname=@Uname and Upass=@Upass and Utype=@Utype";
            SqlCommand sqlCommand1 = new SqlCommand(str,con);
                    
            if (Lotb_Uname.Text == "" || Lotb_Upass.Text == "" || Locb_Utype.Text == "")
            {
                MessageBox.Show("请将信息补充完整！");
            }
            else
            {
                try
                {            
                    sqlCommand1.Parameters.AddWithValue("@Uname", Lotb_Uname.Text);
                    sqlCommand1.Parameters.AddWithValue("@Upass", Lotb_Upass.Text);
                    sqlCommand1.Parameters.AddWithValue("@Utype", Locb_Utype.Text);
                    SqlDataReader sdr = sqlCommand1.ExecuteReader();
                    bool b = sdr.Read();
                    name = Lotb_Uname.Text;
                    if (b == false)
                    {
                        MessageBox.Show("输入错误！请重新输入！");
                    }
                    else
                    {
                        PersenInfo[] personInfo =
                        {
                            new StudentInfo (Lotb_Uname.Text, Lotb_Upass.Text),
                            new TeacherInfo(Lotb_Uname.Text, Lotb_Upass.Text),
                            new ManagerInfo(Lotb_Uname.Text, Lotb_Upass.Text),
                        
                        };
                        
                       if (Locb_Utype.Text == "管理员")
                        {
                            personInfo[2].Show();
                        }
                        else
                        {
                            if (Locb_Utype.Text == "学生")
                            {
                               // Student stu = new Student();
                               // stu.Show();
                                personInfo[0].Show();
              
                            }
                            else
                            {
                                
                                //Teacher tea = new Teacher();
                                //tea.Show();
                                personInfo[1].Show();
                            }
                        }
                    }
   
                    sdr.Close();
               
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.ToString());
                }
                finally
                {
                    sqlCommand1.Parameters.RemoveAt("@Uname");
                    sqlCommand1.Parameters.RemoveAt("@Upass");
                    sqlCommand1.Parameters.RemoveAt("@Utype");
                    con.Close();
                }
            }
            Lotb_Uname.Text = "";
            Lotb_Upass.Text = "";
            Locb_Utype.Text = "";            
        }   
在哪里加代码可以解决这个问题啊？
求高手指教。      

出口处加Close();

加了后两个界面都关了。怎么回事？

你加的位置不对

隐藏一下登录窗体
this.Hide();

这个嘛，上次回答没有仔细看你的代码，实在对不起！
如果是我，我会这样解决：
不在登录界面直接显示别的窗体，登录成功后，判断登录者身份，然后发出一个事件传递登录者身份，调用登录窗体的窗体接收事件再根据身份显示你所谓的别的窗体，登录窗体发出事件后就可以关闭了，不会导致别的窗体关闭。

[ 本帖最后由 mmxo 于 2012-11-20 19:46 编辑 ]

在其他窗体show的同时，用this.Hide()隐藏登陆窗体或用this.close（）关闭登陆窗体！

this.close()