VC 数据库调用的相关知识

				// one.cpp : Defines the class behaviors for the application.
				//
				
				#include "stdafx.h"
				#include "one.h"
				#include "oneDlg.h"
				
				#ifdef _DEBUG
				#define new DEBUG_NEW
				#undef THIS_FILE
				static char THIS_FILE[] = __FILE__;
				#endif
				
				/////////////////////////////////////////////////////////////////////////////
				// COneApp
				
				BEGIN_MESSAGE_MAP(COneApp, CWinApp)
					//{{AFX_MSG_MAP(COneApp)
						// NOTE - the ClassWizard will add and remove mapping macros here.
						//    DO NOT EDIT what you see in these blocks of generated code!
					//}}AFX_MSG
					ON_COMMAND(ID_HELP, CWinApp::OnHelp)
				END_MESSAGE_MAP()
				
				/////////////////////////////////////////////////////////////////////////////
				// COneApp construction
				
				COneApp::COneApp()
				{
					// TODO: add construction code here,
					// Place all significant initialization in InitInstance
				}
				
				/////////////////////////////////////////////////////////////////////////////
				// The one and only COneApp object
				
				COneApp theApp;
				
				/////////////////////////////////////////////////////////////////////////////
				// COneApp initialization
				
				BOOL COneApp::InitInstance()
				{
					AfxEnableControlContainer();
				    AfxOleInit();//james
				
				//////////////////////james
				  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
				  }
				/////////////////////james
					// Standard initialization
					// If you are not using these features and wish to reduce the size
					//  of your final executable, you should remove from the following
					//  the specific initialization routines you do not need.
				
				#ifdef _AFXDLL
					Enable3dControls();			// Call this when using MFC in a shared DLL
				#else
					Enable3dControlsStatic();	// Call this when linking to MFC statically
				#endif
				
					COneDlg dlg;
					m_pMainWnd = &dlg;
					int nResponse = dlg.DoModal();
					if (nResponse == IDOK)
					{
						// TODO: Place code here to handle when the dialog is
						//  dismissed with OK
					}
					else if (nResponse == IDCANCEL)
					{
						// TODO: Place code here to handle when the dialog is
						//  dismissed with Cancel
					}
				
					// Since the dialog has been closed, return FALSE so that we exit the
					//  application, rather than start the application's message pump.
					return FALSE;
				}
				
				int COneApp::ExitInstance() 
				{
					// TODO: Add your specialized code here and/or call the base class
					if(m_pConnection->State) /////////james
					m_pConnection->Close(); 
					return CWinApp::ExitInstance();
				}