VC6.0++ 连接数据库的两种方法

bool CMyDataBase::InitDataBase()
{
 //初始化数据库连接

 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=DataBase.mdb","","",adModeUnknown);///连接数据库
   //hr = m_pConnection->Open("studb","","",adModeUnknown);
  }
 }
 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
 } 
return TRUE;
}

=======================================================================

bool CMyDataBase::InitDataBase()
{
 //初始化数据库连接
 HRESULT hr;
 try
 {
  //实例化连接对象
  hr=m_pConnection.CreateInstance(__uuidof(Connection));
  if(SUCCEEDED(hr))
         {
   //设置连接串属性为UDL文件
   m_pConnection->ConnectionString="File Name=my_data1.udl";
   //设置等待连接打开的时间为20秒
   m_pConnection->ConnectionTimeout=20;
              hr=m_pConnection->Open("","","",adConnectUnspecified);
       if(FAILED(hr))
   {
     AfxMessageBox("open fail!");
  //   return TRUE;
   }
  }
  else
  {
   AfxMessageBox("createinstance of Connection fail!");
  }
 }
     catch (_com_error e)
 {
   _bstr_t bstrSource(e.Source());
   _bstr_t bstrDescription(e.Description());
         AfxMessageBox(bstrSource+bstrDescription);
 }

 return TRUE;
}

[oledb]
; Everything after this line is an OLE DB initstring
Provider=Microsoft.Jet.OLEDB.4.0;Data Source=DataBase.mdb;Persist Security Info=False

双击运行my_data1.udl，会弹出如下图的窗口：