关闭和登陆的时候会报错

Question

在登陆界面的时候,帐号和密码输完了,点击登陆会报错,不是帐号和密码有错,可能是数据库出错,然后点退出的时候出报错.
错误如下图:

Answer 1

这是主窗体代码:unit MainForm;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Menus, ComCtrls;type
  TMain = class(TForm)
    MainMenu1: TMainMenu;
    N1: TMenuItem;
    N2: TMenuItem;
    N3: TMenuItem;
    N4: TMenuItem;
    procedure N1Click(Sender: TObject);
    procedure N4Click(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure FormCreate(Sender: TObject);
    procedure N3Click(Sender: TObject);
    //procedure ShowHint(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Main: TMain;
  jj:integer;implementation
uses InfoForm,landForm,Findform;{$R *.dfm}procedure TMain.N1Click(Sender: TObject);
begin
      APPLICATION.CreateForm(TInfo,Info);
      Info.ShowModal;
      Info.Free;
end;procedure TMain.N4Click(Sender: TObject);
begin
    Application.Terminate;
end;procedure TMain.FormClose(Sender: TObject; var Action: TCloseAction);
begin
    Application.Terminate;
end;procedure TMain.FormCreate(Sender: TObject);
begin
      jj:=0;
      if jj = 0 then
           begin
              APPLICATION.CreateForm(TLanding,Landing);
              Landing.ShowModal;
              Landing.Free;
           end;
      //application.Hint;end;procedure TMain.N3Click(Sender: TObject);
begin
      APPLICATION.CreateForm(Tfind,find);
      find.ShowModal;
      find.Free;
end;end.

Answer 2

这是登陆窗体代码:unit LandForm;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, DB, ADODB;type
  TLanding = class(TForm)
    Label1: TLabel;
    Label2: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
    Button1: TButton;
    Button2: TButton;
    ADOConnection1: TADOConnection;
    ADOQuery1: TADOQuery;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Edit1KeyPress(Sender: TObject; var Key: Char);
    procedure Edit2KeyPress(Sender: TObject; var Key: Char);
    procedure FormCreate(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Landing: TLanding;implementation
uses MainForm;{$R *.dfm}procedure TLanding.Button1Click(Sender: TObject);
begin
    with ADOQuery1 do
      begin
      close;
      sql.clear;
      sql.add('select * from UserForm where Tname = :Tname');
      Parameters.ParamByName('Tname').Value:=edit1.Text;
      Open;
      end;
      if (ADOQuery1.RecordCount=1) and (ADOQuery1.FieldByName('loginpass').AsString=edit2.Text) then
          begin
              self.Close;
              //Main:=TMain.Create(application);
              //Main.ShowModal;
          end
      else
          begin
          MessageDlg('用户名或密码有错!',mtinformation,[mbok],0);
          edit1.SetFocus;
          end;
end;procedure TLanding.Button2Click(Sender: TObject);
begin
   application.Terminate;
end;procedure TLanding.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
    if key = #13 then
      Button1.Click
    else
        if key = #27 then
            Button2.Click;
end;procedure TLanding.Edit2KeyPress(Sender: TObject; var Key: Char);
begin
    if key = #13 then
      Button1.Click
    else
        if key = #27 then
            Button2.Click;
end;procedure TLanding.FormCreate(Sender: TObject);
begin
   jj:=1;
   Edit1.Text:='';
   Edit2.Clear;
end;procedure TLanding.FormClose(Sender: TObject; var Action: TCloseAction);
begin
    Application.Terminate;
end;end.

Answer 3

你的landing这个form是auto-create 还是avaliable form?

Answer 4

动态设置ado数据连接的参数即可，你的这个登陆窗体和主窗体的关系可能也有问题

Answer 5

不太明白什么是动态数据连接?
是指手动写ADO的连接吗?

Answer 6

登录窗口如果是在程序中自动加载的话可以用这个方式,在view source里面写，然后在登录窗口中判断是否登录成功~~!
 
  begin
  Application.Initialize;
  Application.ShowMainForm  :=  False;
  Application.CreateForm(TFrmMain, FrmMain);
  Application.CreateForm(TFrmLogin, FrmLogin);
  if FrmLogin.ShowModal   =mrCancel then   //取消登录主窗口自动退出，程序自动退出
     FrmMain.Close
  else
     FrmMain.Show;
  Application.Run;
end.
 如果是在主窗口中加载，最好取消登录窗口的自动加载，procedure TFrmMain.FormCreate(Sender: TObject);
begin
  Application.CreateForm(TFrmLogin, FrmLogin);
  if FrmLogin.ShowModal   =mrCancel then    //取消登录主窗口自动退出，程序也自动退出
     FrmMain.Close;
  FrmLogin.free;
end;你的代码中主窗口创建后马上又创建了登录窗口，但是登录窗口不管作何处理，只要关闭了登录窗口，主程序就会退出，
procedure TLanding.FormClose(Sender: TObject; var Action: TCloseAction); 
begin 
    Application.Terminate; 
end; 
但是此时主窗口只是刚刚创建完成，主程序就执行了Application.Terminate，所以有些事件没有执行完或是对象没有释放，所以会报错~~!