unit1.pas

< SQL SERVER 2000 案例教程>>,冶金工业出版社,这本书的代码

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs,Unit2,inifiles, StdCtrls, Buttons, ExtCtrls;

type
  Tlogin = class(TForm)
    Edit1: TEdit;
    Label1: TLabel;
    Edit2: TEdit;
    Label2: TLabel;
    BitBtn1: TBitBtn;
    BitBtn2: TBitBtn;
    procedure BitBtn2Click(Sender: TObject);
    procedure BitBtn1Click(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  login: Tlogin;
  username,userpower:string;
implementation

{$R *.dfm}

uses Unit3;
procedure Tlogin.BitBtn2Click(Sender: TObject);
begin
  application.Terminate;
end;

procedure Tlogin.BitBtn1Click(Sender: TObject);
begin
  //使用with语句使用Data Module中的Query组件
  with mydata.Query1 do
  begin
    close; //关闭Query1，否则不能写入SQL语句
    with SQL do //使用Query1的SQL属性
    begin
      clear;  //先清除SQL属性中的内容，以免影响下面操作
      //添加SQL代码，使用参数化方法，注意在参数前面一定要使用：号
      Add('select * from  用户密码表 where 用户名=:uname and 用户密码=:upassword');
      //给各参数赋值
      ParamByName('uname').AsString:=Edit1.Text;
      ParamByName('upassword').AsString:=trim(Edit2.Text);
    end;
    open;//执行SQL语句
    if(mydata.Query1.FindLast) then   //判断查询结果是否为空
    begin
    //如果该用户名和密码正确，则隐藏登录窗体，显示主窗体，main为主窗体名
      main.Show();
      login.Hide;
    end
    else
    begin
        //提示出错信息
       showmessage('用户名或密码错误，请重新输入');
    end;
  end;
end;
procedure Tlogin.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  application.Terminate;
end;

end.