formlogin.pas

Delphi数据库编程

unit FormLogin;

interface

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

type
  TfrmLogin = class(TForm)
    btnOK: TButton;
    btnQuit: TButton;
    edtUserID: TEdit;
    edtPasswd: TEdit;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    qryUsers: TQuery;
    Database1: TDatabase;
    procedure btnOKClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    Times: Byte;
  public
    { Private declarations }
  end;

var
  frmLogin: TfrmLogin;

implementation

{$R *.dfm}

procedure TfrmLogin.FormCreate(Sender: TObject);
begin
  Times := 0;
end;

procedure TfrmLogin.btnOKClick(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);
      TheEdit.SetFocus;
      Abort;
    end;
  end;
begin
  CheckInput(edtUserID, '请输入用户名！');
  CheckInput(edtPasswd, '请输入密码！');

  qryUsers.Active := false;
  qryUsers.ParamByName('UserID').AsString := edtUserID.Text;
  qryUsers.ParamByName('Passwd').AsString := edtPasswd.Text;
  qryUsers.Active := true;

  if qryUsers.Eof then
  begin
    ShowMessage('用户名或者口令不正确！');
    edtUserID.SetFocus;
    Inc(Times);
  end
  else
    ModalResult := mrOK;

  if times >= 3 then
  begin
    ShowMessage('非法用户无权登录！');
    ModalResult := mrCancel;
  end;
end;

end.