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结合ADO、ADOX和MFC的文档/视图/框架架构创建和打开Access数据库

时间:2021-07-01 10:21:17 帮助过:11人阅读

本文描述了如何在MFC的文档/视图/框架架构中使用ADO和ADOX来创建和打开数据库。 预备阅读 MFC技术文章 TN025: Document, View, and Frame Creation 微软知识库文章 Q183606 ActiveX Data Objects (ADO) Frequently Asked Questions Q169496 INFO: Using Acti

本文描述了如何在MFC的文档/视图/框架架构中使用ADO和ADOX来创建和打开数据库。

预备阅读

MFC技术文章

  • TN025: Document, View, and Frame Creation

微软知识库文章

  • Q183606 ActiveX Data Objects (ADO) Frequently Asked Questions
  • Q169496 INFO: Using ActiveX Data Objects (ADO) via #import in VC++
  • Q317881 HOW TO: Create an Access Database Using ADOX and Visual C# .NET
  • Q252908 HOWTO: Create a Table with Primary Key Through ADOX
  • Q201826 PRB: Error 3265 When You Access Properties Collection

Office VBA参考

  • Creating and Modifying Access Tables

步骤

  1. 在计算机上安装MDAC2.5以上版本
  2. 打开VC。首先,我们使用MFC应用程序向导创建一个标准的MDI程序,这里我为这个工程起名为Passport,然后在stdafx.h中导入ADOX
    #include
    #import "c:/Program Files/Common Files/system/ado/Msado15.dll" rename("EOF","adoEOF") rename("DataTypeEnum","adoDataTypeEnum")
    #import "c:/Program Files/Common Files/System/ADO/Msadox.dll" rename("EOF", "adoXEOF") rename("DataTypeEnum","adoXDataTypeEnum")
    #import "c:/PROGRAM FILES/COMMON FILES/System/ado/MSJRO.DLL"

    根据你的计算机上ADO的安装路径,这里的路径可能有所不同。
  3. 在文档类中声明数据库连接 ADODB::_ConnectionPtr m_pConn;和记录集 ADODB::_RecordsetPtr m_pSet;,并且重载文档类的DeleteContents() 、OnNewDocument()和OnOpenDocument()函数,用于断开数据库连接,创建数据库和表,以及打开现有的数据库。
    (作者的抱怨:CSDN文章中心该改改了,代码排版这么麻烦)
    void CPassportDoc::DeleteContents()
    {
    try
    {
    if(m_pSet){
    ESRecordsetClose(m_pSet);
    }
    if(m_pConn)
    if(m_pConn->State&ADODB::adStateOpen)
    m_pConn->Close();
    m_pConn=NULL;
    }
    catch(_com_error &e){
    ESErrPrintProviderError(m_pConn);
    ESErrPrintComError(e);
    }
    CDocument::DeleteContents();
    }BOOL CPassportDoc::OnNewDocument()
    {
    if (!CDocument::OnNewDocument())
    return FALSE;
    CFileDialog dlgFile(FALSE, _T(".mdb"), NULL, OFN_HIDEREADONLY | OFN_PATHMUSTEXIST, _T("Access 数据库 (*.mdb)|*.mdb|全部文件(*.*)|*.*||"));
    if (dlgFile.DoModal() != IDOK)
    return FALSE;
    CString strDBPath=dlgFile.GetPathName();
    if(!CreateDB(strDBPath))return FALSE;
    //create
    CString strConnect;

    strConnect.Format(_T("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=%s"),strDBPath);
    COleVariant Connect(strConnect);
    // TODO: add reinitialization code here
    // (SDI documents will reuse this document)
    try{
    m_pConn.CreateInstance(_T("ADODB.Connection"));
    m_pSet.CreateInstance(_T("ADODB.Recordset"));
    m_pConn->PutCommandTimeout(30);
    m_pConn->PutConnectionTimeout(30);
    m_pConn->put_CursorLocation(ADODB::adUseClient);
    m_pConn->Open(_bstr_t(strConnect),_bstr_t(),_bstr_t(),ADODB::adConnectUnspecified);
    ::ESRecordsetOpen(_T("Passport"),m_pConn,m_pSet);
    SetPathName(strDBPath);
    return TRUE;
    }
    catch(_com_error &e){
    ESErrPrintProviderError(m_pConn);
    ESErrPrintComError(e);
    }
    catch(...){
    }
    m_pConn=NULL;
    return FALSE;
    }
    BOOL CPassportDoc::OnOpenDocument(LPCTSTR lpszPathName)
    {
    if (!CDocument::OnOpenDocument(lpszPathName))
    return FALSE;
    ADODB::_ConnectionPtr tempConnn;
    CString strConnect;
    CString strDBPath=lpszPathName;
    strConnect.Format(_T("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=%s"),strDBPath);
    COleVariant Connect(strConnect);
    // TODO: add reinitialization code here
    // (SDI documents will reuse this document)
    try{
    tempConnn.CreateInstance(_T("ADODB.Connection"));
    tempConnn->PutCommandTimeout(30);
    tempConnn->PutConnectionTimeout(30);
    tempConnn->put_CursorLocation(ADODB::adUseClient);
    tempConnn->Open(_bstr_t(strConnect),_bstr_t(),_bstr_t(),ADODB::adConnectUnspecified);
    SetPathName(strDBPath);
    m_pConn=tempConnn;
    m_pSet=NULL;
    m_pSet.CreateInstance(_T("ADODB.Recordset"));
    ::ESRecordsetOpen(_T("Passport"),m_pConn,m_pSet);
    UpdateAllViews(NULL,UpdateHintRefresh);
    return TRUE;
    }
    catch(_com_error &e){
    ESErrPrintProviderError(tempConnn);
    ESErrPrintComError(e);
    }
    catch(...){
    }
    return FALSE;
    }
  4. 编写一个辅助函数,用于创建数据库、表和索引
    BOOL CPassportDoc::CreateDB(LPCTSTR lpszFile)
    {
    if(::PathFileExists(lpszFile)){
    CString strTemp;
    strTemp.Format(IDS_TARGET_EXISTS,lpszFile);
    AfxMessageBox(lpszFile);
    return FALSE;
    }
    ADODB::_ConnectionPtr tempConnn;
    ADOX::_CatalogPtr pCatalog = NULL;
    ADOX::_TablePtr pTable = NULL;
    ADOX::_IndexPtr pIndexNew = NULL;
    ADOX::_IndexPtr pIndex = NULL;
    CString strConnect;
    CString strDBPath=lpszFile;
    strConnect.Format(_T("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=%s"),strDBPath);
    COleVariant Connect(strConnect);
    try{
    pCatalog.CreateInstance(_T("ADOX.Catalog"));
    pCatalog->Create((LPCTSTR)strConnect);//创建数据库
    tempConnn.CreateInstance(_T("ADODB.Connection"));
    tempConnn->PutCommandTimeout(30);
    tempConnn->PutConnectionTimeout(30);
    tempConnn->put_CursorLocation(ADODB::adUseClient);
    tempConnn->Open(_bstr_t(strConnect),_bstr_t(),_bstr_t(),ADODB::adConnectUnspecified);
    pCatalog->PutActiveConnection(_variant_t((IDispatch *) tempConnn));
    pTable.CreateInstance(_T("ADOX.Table"));
    pTable->ParentCatalog =pCatalog;
    pTable->Name="Passport";
    ADOX::ColumnsPtr pCols =pTable->Columns;
    pCols->Append(_T("RecordID") ,ADOX::adInteger,0);//自动编号字段
    pCols->Append(_T("Name") ,ADOX::adWChar,255);//文本字段
    pCols->Append(_T("DateOfBirth") ,ADOX::adDate,0);//日期字段
    pCols->Append(_T("OtherInfo"),ADOX::adLongVarWChar,0);//备注字段
    pCatalog->Tables->Refresh();
    long lCount=pCols->Count;
    for(long i=0;i pCols->GetItem(i)->ParentCatalog =pCatalog;//重要!设置Catalog,参见Q201826 PRB: Error 3265 When You Access Properties Collection
    ADOX::PropertiesPtr pProperties=pCols->GetItem(i)->Properties;
    if(pProperties){//这里是用于调试的属性显示代码
    long lp=pProperties->Count;
    TRACE("Properties for Col %s/r/n",(LPCTSTR)pCols->GetItem(i)->Name);
    for(long j=0;j TRACE("/rProperty %s:%s/r/n",g_GetValueString(pProperties->GetItem(j)->Name)
    ,g_GetValueString(pProperties->GetItem(j)->Value));
    }
    }
    }
    pCols->GetItem(_T("RecordID"))->Properties->GetItem(_T("Description"))->Value=_T("记录编号");//注释
    pCols->GetItem(_T("RecordID"))->Properties->GetItem(_T("AutoIncrement"))->Value=true;//自动编号
    pCols->GetItem(_T("Name"))->Properties->GetItem(_T("Jet OLEDB:Compressed UniCode Strings"))->Value=true;
    pCols->GetItem(_T("Name"))->Properties->GetItem(_T("Description"))->Value=_T("姓名");
    pCols->GetItem(_T("DateOfBirth"))->Properties->GetItem(_T("Description"))->Value=_T("出生日期");
    pCols->GetItem(_T("OtherInfo"))->Properties->GetItem(_T("Jet OLEDB:Compressed UniCode Strings"))->Value=true;
    pCols->GetItem(_T("OtherInfo"))->Properties->GetItem(_T("Description"))->Value=_T("其他信息");
    pCatalog->Tables->Append(_variant_t ((IDispatch*)pTable));//添加表
    pCatalog->Tables->Refresh();//刷新
    pIndexNew.CreateInstance(_T("ADOX.Index"));
    pIndexNew->Name = "RecordID";//索引名称
    pIndexNew->Columns->Append("RecordID",ADOX::adInteger,0);//索引字段
    pIndexNew->PutPrimaryKey(-1);//主索引
    pIndexNew->PutUnique(-1);//唯一索引
    pTable->Indexes->Append(_variant_t ((IDispatch*)pIndexNew));//创建索引
    pIndexNew=NULL;
    pCatalog->Tables->Refresh();//刷新
    return TRUE;
    }
    catch(_com_error &e){
    ESErrPrintProviderError(tempConnn);
    ESErrPrintComError(e);
    return FALSE;
    }
    catch(...){
    }
    return FALSE;
    }
  5. 辅助的数据库函数。由于这些函数是Jiangsheng以前为一个项目写的。所以命名有些奇怪。借鉴了MFC类CDaoRecordset的部分代码
    #define _countof(array) (sizeof(array)/sizeof(array[0]))
    BOOL ESRecordsetOpen(
    LPCTSTR lpszSQL
    ,ADODB::_ConnectionPtr pConnection
    ,ADODB::_RecordsetPtr& rst
    ,ADODB::CursorTypeEnum CursorType//=adOpenDynamic
    ,ADODB::LockTypeEnum LockType//=ado20::adLockOptimistic
    ,long lOptions//=adCmdUnspecified
    )
    {
    _bstr_t bstrQuery;
    const TCHAR _afxParameters2[] = _T("PARAMETERS ");
    const TCHAR _afxSelect2[] = _T("SELECT ");
    const TCHAR _afxTransform2[] = _T("TRANSFORM ");
    const TCHAR _afxTable2[] = _T("TABLE ");
    // construct the default query string
    if ((_tcsnicmp(lpszSQL, _afxSelect2, _countof(_afxSelect2)-1) != 0) &&
    (_tcsnicmp(lpszSQL, _afxParameters2, _countof(_afxParameters2)-1) != 0) &&
    (_tcsnicmp(lpszSQL, _afxTransform2, _countof(_afxTransform2)-1) != 0) &&
    (_tcsnicmp(lpszSQL, _afxTable2, _countof(_afxTable2)-1) != 0)){
    CString strTemp;
    strTemp.Format("SELECT * FROM (%s)",lpszSQL);
    bstrQuery=(LPCTSTR)strTemp;
    }
    else
    bstrQuery=lpszSQL;
    if(rst!=NULL){
    rst->CursorLocation=ADODB::adUseClient;
    rst->Open(bstrQuery,_variant_t(pConnection.GetInterfacePtr(),true),CursorType,LockType,lOptions);
    }
    TRACE("Open Recordset:%s/n",lpszSQL);
    return ESRecordsetIsOpen(rst);
    }
    BOOL ESRecordsetIsOpen(const ADODB::_RecordsetPtr& rst)
    {
    if(rst!=NULL){
    return rst->State&ADODB::adStateOpen;
    }
    return FALSE;
    }
    void ESRecordsetClose(ADODB::_RecordsetPtr& rst)
    {
    if(rst!=NULL){
    if(rst->State&ADODB::adStateOpen)
    rst->Close();
    }
    }
    CString g_GetValueString(const _variant_t& val)
    {
    CString strVal;
    _variant_t varDest(val);
    if(!g_varIsValid(val)){
    return strVal;
    }
    if(val.vt==VT_BOOL){
    if(val.boolVal==VARIANT_FALSE){
    return _T("否");
    }
    else
    return _T("是");
    }
    else{
    }
    if(varDest.vt!=VT_BSTR){
    HRESULT hr=::VariantChangeType(&varDest,&varDest,VARIANT_NOUSEROVERRIDE|VARIANT_LOCALBOOL,VT_BSTR);
    if(FAILED(hr)){
    return strVal;
    }

    }
    strVal=(LPCTSTR)_bstr_t(varDest);
    return strVal;
    }
  6. 错误处理代码
    void ESErrPrintComError(_com_error &e)
    {
    _bstr_t bstrSource(e.Source());
    _bstr_t bstrDescription(e.Description());
    CString strTemp;
    strTemp.Format(_T("´错误/n/t错误代码: %08lx/n/t含义: %s/n/t来自 : %s/n/t描述 : %s/n"),
    e.Error(),e.ErrorMessage(),(LPCSTR) bstrSource,(LPCSTR) bstrDescription);
    // Print COM errors.
    ::AfxMessageBox(strTemp);
    #ifdef _DEBUG
    AfxDebugBreak();
    #endif
    }
    void ESErrPrintProviderError(ADODB::_ConnectionPtr pConnection)
    {
    if(pConnection==NULL) return;
    try{
    // Print Provider Errors from Connection object.
    // pErr is a record object in the Connection's Error collection.
    ADODB::ErrorPtr pErr = NULL;
    ADODB::ErrorsPtr pErrors=pConnection->Errors;
    if(pErrors){
    if( (pErrors->Count) > 0){
    long nCount = pErrors->Count;
    // Collection ranges from 0 to nCount -1.
    for(long i = 0;i < nCount;i++){
    pErr = pErrors->GetItem(i);
    CString strTemp;
    strTemp.Format(_T("/t 错误代码: %x/t%s"), pErr->Number, pErr->Description);
    }
    }
    }
    }
    catch(_com_error &e){
    ESErrPrintComError(e);
    }
    }

总结

在文档/视图/框架架构中集成数据库访问总体来说还是难度不大的。微软提供了很多示例的代码,大部分工作只是把示例代码从其他语言改写到VC。主要的工作是对MFC的文档/视图/框架架构的理解,在适当的时候调用这些代码。

尽管我在打开数据库的同时也打开了一个记录集,但是我并未给出显示记录集内容的代码,这超出了本文的范围。我可以给出的提示是使用现成的数据列表控件来显示,微软知识库文章Q229029 SAMPLE: AdoDataGrid.exe Demonstrates How to Use ADO with DataGrid Control Using Visual C++可以作为参考。

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