VC如何中如何连接access？

阳光穿透心脏的1/2处 2022-05-13 00:12 252阅读 0赞

实现用access简单的登录功能：

![1354592081_9529.jpg][]

首先建立个access数据库login.mdb：

新建一个表UserInfo，包括两个字段UserName和PassWord.都是文本类型。

![1354597311_9417.jpg][]

界面字面变量定义：

![1354597470_1048.jpg][]

导入类库：

在StdAfx.h添加代码

#import "C:\Program Files\Common Files\System\ado\msado15.dll" no_namespace rename("EOF","adoEOF")

在app类中声明连接对象

class CAdoAccessTest1App : public CWinApp
    {
    public:
    
    	//声明连接对象
    	_ConnectionPtr m_pConnection;
    	
    
    	CAdoAccessTest1App();
    
    // Overrides
    	// ClassWizard generated virtual function overrides
    	//{
        {AFX_VIRTUAL(CAdoAccessTest1App)
    	public:
    	virtual BOOL InitInstance();
    	virtual int ExitInstance();
    	//}}AFX_VIRTUAL
    
    // Implementation
    
    	//{
        {AFX_MSG(CAdoAccessTest1App)
    		// NOTE - the ClassWizard will add and remove member functions here.
    		//    DO NOT EDIT what you see in these blocks of generated code !
    	//}}AFX_MSG
    	DECLARE_MESSAGE_MAP()
    };

在app中的InitInstance()中添加初始化代码：

AfxEnableControlContainer();
    
    	// 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.
    
    
    	//初始化com库
    	CoInitialize(NULL);
    
    	try
    	{
    		HRESULT hr;
    		
    		//创建Connection实例对象
    		hr = m_pConnection.CreateInstance("ADODB.Connection");
    		
    		if(SUCCEEDED(hr))
    		{
    			m_pConnection->ConnectionTimeout = 8;//设置超时时间为8秒
    			m_pConnection->PutCursorLocation(adUseClient);//这是设置游标的，游标在服务器端还是客户端决定了你能够采用的打开模式 ，不同的数据库支持不同。
    			hr = m_pConnection->Open("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=.\\login.mdb;Persist Security Info=False","","",adModeUnknown);		
    			
    		}
    
    	}
    	catch (_com_error e)
    	{//异常处理
    
    		CString temp;
    		temp.Format("连接数据库错误信息:%s",e.ErrorMessage());
    		::MessageBox(NULL,temp,"提示信息",NULL);
    		return FALSE;	
    	}
    
    
    
    #ifdef _AFXDLL

引用theApp变量，注意添加extern关键字：

extern CAdoAccessTest1App theApp;

相应登录按钮的函数：

void CAdoAccessTest1Dlg::OnOK() 
    {
    	// TODO: Add extra validation here
    
    	//更新数据
    	UpdateData(TRUE);
    
    	//初始化记录集
    	_RecordsetPtr pRs("ADODB.Recordset");
    
    	//构建SQL语句
    	CString strSQL;
    	strSQL.Format("select * from UserInfo where UserName = '%s' and PassWord = '%s'",m_sUserName,m_sPassword );
    
    	//打开指点记录集
    	pRs->Open(_variant_t(strSQL.GetBuffer(strSQL.GetLength())),
    		_variant_t(theApp.m_pConnection,true),
    		adOpenStatic,
    		adLockOptimistic,
    		adCmdText
    
    		);
    
    	//访问记录集中的数据
    	if(pRs->GetRecordCount() > 0)
    	{
    		MessageBox("登录成功！！");
    	}
    	else
    	{
    		MessageBox("登录失败！！");
    	}
    
    	//关闭记录集
    	pRs->Close();
    
    	
    //	CDialog::OnOK();
    }

在app类中的ExitInstance()函数释放资源：

int CAdoAccessTest1App::ExitInstance() 
    {
    	// TODO: Add your specialized code here and/or call the base class
    
    	if(m_pConnection->State)
    	{
    		//释放资源
    		m_pConnection->Close();
    		m_pConnection.Release();
    	}
    	
    	return CWinApp::ExitInstance();
    }

[1354592081_9529.jpg]: https://img-my.csdn.net/uploads/201212/04/1354592081_9529.jpg
[1354597311_9417.jpg]: https://img-my.csdn.net/uploads/201212/04/1354597311_9417.jpg
[1354597470_1048.jpg]: https://img-my.csdn.net/uploads/201212/04/1354597470_1048.jpg