userlogin.pas

Delphi+SQL的学生信息管理系统

unit userlogin;

interface

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

type
  Tfrmlogin = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    edtuserID: TEdit;
    edtpasswd: TEdit;
    Database1: TDatabase;
    queryuser: TQuery;
    Bevel1: TBevel;
    Label1: TLabel;
    procedure Button2Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure edtpasswdKeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    procedure edtuserIDKeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  frmlogin: Tfrmlogin;
  times:integer;
implementation

{$R *.dfm}



procedure Tfrmlogin.Button2Click(Sender: TObject);
begin
close;
end;

procedure Tfrmlogin.FormCreate(Sender: TObject);
begin
times:=0;
end;

procedure Tfrmlogin.Button1Click(Sender: TObject);
 procedure checkInput(TheEdit:TEdit;strDesc:string);
 begin
 TheEdit.Text:=trim(theedit.Text);
 TheEdit.Text:=stringReplace(theedit.Text,'''','',[rfreplaceall]);
 TheEdit.Text:=stringreplace(theedit.Text,'','',[rfreplaceall]);
 if TheEdit.Text='' then
  begin
   showmessage(strDesc);
   edtuserID.SetFocus;
   abort;
   end;
  end;
begin
   checkInput(edtuserID,'请输入用户号');
   checkInput(edtpasswd,'请输入密码');
   queryuser.Close;
   queryuser.SQL.Clear;
   queryuser.SQL.Add('select * from users where userID='+''''+edtuserID.Text+''''+'and '+'passwd='+''''+edtpasswd.Text+'''' );
   queryuser.Open;
   if queryuser.Eof then
   begin
    showmessage('用户号或密码不正确');
    edtuserID.SetFocus;
    inc(times);
    end
   else
   begin
    if times>=3 then
     begin
     showmessage('非法用户不能登陆系统');
     modalresult:=mrcancel;
     end
     else
     modalresult:=mrOK;
    end;
end;



procedure Tfrmlogin.FormClose(Sender: TObject; var Action: TCloseAction);
begin
action:=cafree;
end;


procedure Tfrmlogin.edtpasswdKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
if key=13 then
  Button1Click(Sender)
else if key=vk_up then
   edtuserID.SetFocus;
end;

procedure Tfrmlogin.edtuserIDKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
if key=13 then
   edtpasswd.SetFocus;
end;


end.