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HomeDatabaseMysql TutorialVC++中使用ADO方式操作ACCESS数据库

欢迎进入C/C++编程社区论坛,与200万技术人员互动交流 >>进入 ADO(ActiveX Data Object)是Microsoft数据库应用程序开发的新接口,是建立在OLE DB之上的高层数据库访问技术,即使你对OLE DB,COM不了解也能轻松对付ADO,因为它非常简单易用,甚至比你以往所

欢迎进入C/C++编程社区论坛,与200万技术人员互动交流 >>进入

    ADO(ActiveX Data Object)是Microsoft数据库应用程序开发的新接口,是建立在OLE DB之上的高层数据库访问技术,即使你对OLE DB,COM不了解也能轻松对付ADO,因为它非常简单易用,甚至比你以往所接触的ODBC API、DAO、RDO都要容易使用,并不失灵活性。本文详细地介绍在Visual C++开发环境下如何使用ADO来进行数据库应用程序开发。

    一、实现方法

    万事开头难,任何一种新技术对于初学者来说最重要的还是"入门",掌握其要点。让我们来看看ADO数据库开发的基本流程吧!它的基本步骤如下:

    (1)初始化COM库,引入ADO库定义文件

    (2)用Connection对象连接数据库

    (3)利用建立好的连接,通过Connection、Command对象执行SQL命令,或利用Recordset对象取得结果记录集进行查询、处理。

    (4)使用完毕后关闭连接释放对象。

    下面我们将详细介绍上述步骤并给出相关代码。

    1、COM库的初始化

    我们可以使用AfxOleInit()来初始化COM库,这项工作通常在CWinApp::InitInstance()的重载函数中完成,请看如下代码:

    BOOL CADOTest1App::InitInstance()

    { AfxOleInit();……

    }

    2、用#import指令引入ADO类型库

    为了引入ADO类型库,需要在项目的stdafx.h文件中加入如下语句:

    #import "c:\program files\common files\system\ado\msado15.dll" no_namespace rename("EOF","adoEOF")

    这一语句有何作用呢?其最终作用同我们已经十分熟悉的#include类似,编译的时候系统会为我们生成msado15.tlh,ado15.tli两个C++头文件来定义ADO库。

    需要读者朋友注意的是:您的开发环境中msado15.dll不一定在这个目录下,请按实际情况修改;在编译的时候可能会出现如下警告,对此微软在MSDN中作了说明,并建议我们不要理会这个警告:msado15.tlh(405) : warning C4146: unary minus operator applied to unsigned type, result still unsigned.

    3、创建Connection对象并连接数据库

    为了首先我们需要添加一个指向Connection对象的指针_ConnectionPtr m_pConnection,下面的代码演示了如何创建Connection对象实例及如何连接数据库并进行异常捕捉:

 BOOL CADOTest1Dlg::OnInitDialog()
{
 CDialog::OnInitDialog();
 HRESULT hr;
 try
 {
  hr = m_pConnection.CreateInstance("ADODB.Connection");///创建Connection对象
  if(SUCCEEDED(hr))
  {
   hr = m_pConnection->Open("Provider=Microsoft.Jet.OLEDB.4.0;
   Data Source=test.mdb","","",adModeUnknown);///连接数据库
   //上面一句中连接字串中的Provider是针对ACCESS2000环境的,对于ACCESS97,
   //需要改为:Provider=Microsoft.Jet.OLEDB.3.51;
  }
 }
 catch(_com_error e)///捕捉异常
 {
  CString errormessage;
  errormessage.Format("连接数据库失败!\r\n错误信息:%s",e.ErrorMessage());
  AfxMessageBox(errormessage);///显示错误信息
 } 

    在这段代码中我们是通过Connection对象的Open方法来进行连接数据库的,下面是该方法的原型:

    HRESULT Connection15::Open ( _bstr_t ConnectionString, _bstr_t UserID, _bstr_t Password, long Options );

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VC++中使用ADO方式操作ACCESS数据库

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