dl.pas

希望大家能多多指教这是我给我们同学编的系统

unit dl;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, DB, DBTables, StdCtrls;

type
  Ttlform = class(TForm)
    Label1: TLabel;
    Edit1: TEdit;
    Label2: TLabel;
    Edit2: TEdit;
    Button1: TButton;
    Button2: TButton;
    Label3: TLabel;
    Query1: TQuery;
    Query1Xingming: TStringField;
    Query1Mima: TStringField;
    Label5: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  tlform: Ttlform;
     count:integer;

  yonghu:string;
  havelogon:boolean;
implementation

uses zct;

{$R *.dfm}

procedure Ttlform.Button1Click(Sender: TObject);
begin
if edit1.Text=''then
    begin
      messageDlg('请输入用户名!',mtInformation,[mbOk],0);
      Edit1.SetFocus ;
      exit;
    end;
 if Edit2.Text =''  then
    begin
      MessageDlg('请输入密码!',mtInformation,[mbOk],0);
      Edit2.SetFocus ;
      exit;
    end;
 if (Edit1.Text<>'') and (Edit2.Text <>'') then
     begin
       count:=count+1;
       Query1.Close;
       Query1.SQL.Clear ;
       Query1.Params.Clear ;
       Query1.Params.CreateParam(ftstring,'xm',ptinput).AsString :=Edit1.Text ;
       Query1.SQL.Add('select * from yonghu where xingming=:xm');
       try
         Query1.Open
       Except
         MessageDlg('无此用户！',mtError,[mbOk],0)
       end;
       if (Edit2.Text=Query1mima.Value) then
          begin
          messagedlg('成功登录',mtInformation,[mbOk],0);
          yonghu:=Edit1.Text;
          havelogon:=true;
          zctform.Show;
          havelogon:=True;
          tlform.close;
          end
       else
          begin
            messageDlg('密码不正确!',mtError,[mbOk],0);
            Edit2.Clear ;
            Edit2.SetFocus ;
            if count=3 then
              begin
                messageDlg('连续登录三次失败，将退出程序!',mtWarning,[mbOk],0);
                Application.Terminate ;
              end;
          end;
    end;
end;

procedure Ttlform.Button2Click(Sender: TObject);
begin
Application.Terminate;
end;

end.