main.pas

Delphi7数据库开发教程,包含该书21套实例

unit main;

interface

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

type
  TForm1 = class(TForm)
    SQLConnection1: TSQLConnection;
    btnConnect: TButton;
    cbxLoginPrompt: TCheckBox;
    lblStatus: TLabel;
    btnDisconnect: TButton;
    memStatus: TMemo;
    procedure btnConnectClick(Sender: TObject);
    procedure SQLConnection1Login(Database: TSQLConnection;
      LoginParams: TStrings);
    procedure SQLConnection1BeforeConnect(Sender: TObject);
    procedure SQLConnection1AfterConnect(Sender: TObject);
    procedure cbxLoginPromptClick(Sender: TObject);
    procedure btnDisconnectClick(Sender: TObject);
    procedure SQLConnection1AfterDisconnect(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btnConnectClick(Sender: TObject);
begin
  SQLConnection1.Connected := True;
end;

procedure TForm1.SQLConnection1Login(Database: TSQLConnection;
  LoginParams: TStrings);
begin
  //LoginPrompt为True时使用该事件处理程序
  LoginParams.Values['User_Name'] := 'sysdba';
  LoginParams.Values['Password'] := 'masterkey';
  //更新状态
  memStatus.Lines.Add('在OnLongin事件中进行身份验证...');
end;

procedure TForm1.SQLConnection1BeforeConnect(Sender: TObject);
begin
 //要建立连接时触发该事件
  with Sender as TSQLConnection do
  begin
    //为了和OnLogin事件处理区分，这里在LoginPrompt为Fasle时才登录
    if LoginPrompt = False then
    begin
      Params.Values['User_Name'] := 'SYSDBA';
      Params.Values['Password'] := 'masterkey';
      //也可以采取加密密码的方式,其中Decrypt是自己定义的解密函数
      //Params.Values['Password'] := Decrypt(Params.Values['Password']);

      //更新状态
      memStatus.Lines.Add('在BeforeConnect事件中进行身份验证...');
    end;
  end;
end;

procedure TForm1.SQLConnection1AfterConnect(Sender: TObject);
begin
  if SQLConnection1.Connected then
     memStatus.Lines.Add('已经登录数据库，后台身份验证成功！');
end;

procedure TForm1.cbxLoginPromptClick(Sender: TObject);
begin
  //设置LoginPrompt属性
  SQLConnection1.LoginPrompt := cbxLoginPrompt.Checked;
end;

procedure TForm1.btnDisconnectClick(Sender: TObject);
begin
  SQLConnection1.Connected := False ;
  memStatus.Lines.Add('断开数据库连接...');
end;

procedure TForm1.SQLConnection1AfterDisconnect(Sender: TObject);
begin
  if not SQLConnection1.Connected then
     memStatus.Lines.Add('已经从数据库断开');
end;

end.