< p >C語言是一種強大的編程語言，而ADO（ActiveX Data Objects）是一個可以訪問數據庫的接口。這篇文章將介紹如何在C語言中使用ADO來連接Oracle數據庫。< p >在C語言中使用ADO訪問Oracle非常方便，我們可以使用Windows API創建一個Connection對象并使用該對象連接到數據庫。例如：< pre >// 定義Connection對象 IDBProperties *pIDBProperties = NULL; ISessionProperties *pISessionProperties = NULL; IDBInitialize *pIDBInitialize = NULL; IDataSourceLocator *pIDataSourceLocator = NULL; IServerLocation *pIServerLocation = NULL; IDBCreateSession *pIDBCreateSession = NULL; IDBDataSourceAdmin *pIDBDataSourceAdmin = NULL; IUnknown *pIUnkOuter = NULL; hr = CoInitialize(NULL); hr = CoCreateInstance(CLSID_MSDAINITIALIZE, NULL, CLSCTX_INPROC_SERVER, IID_IDBInitialize, (void**)&pIDBInitialize); hr = pIDBInitialize->QueryInterface(IID_IDBProperties, (void**)&pIDBProperties); hr = pIDBProperties->SetProperties(0, 0, 0, 0); hr = pIDBInitialize->Initialize(); hr = CoCreateInstance(CLSID_MSDAORA, NULL, CLSCTX_INPROC_SERVER, IID_IDBCreateSession, (void**)&pIDBCreateSession); hr = pIDBCreateSession->CreateSession(NULL, IID_ISessionProperties, (IUnknown**)&pISessionProperties); hr = pISessionProperties->SetProperties(0, 0, 0, strConnectString, lstrlen(strConnectString)); hr = pISessionProperties->QueryInterface(IID_IServerLocation, (void**)&pIServerLocation);< p >上述代碼使用了MSDAORA的類庫來連接到Oracle數據庫，并創建了一個ISessionProperties對象，該對象可以讓我們進行更多的數據庫操作。< p >接下來，我們可以執行SQL語句來對數據庫進行操作。例如：< pre >// 定義Command對象 IDBCreateCommand *pIDBCreateCommand = NULL; ICommandText *pICommandText = NULL; hr = pIDBCreateSession->CreateSession(NULL, IID_IDBCreateCommand, (IUnknown**)&pIDBCreateCommand); hr = pIDBCreateCommand->CreateCommand(NULL, IID_ICommandText, (IUnknown**)&pICommandText); hr = pICommandText->SetCommandText(strSQL); hr = pICommandText->Execute(NULL, IID_NULL, NULL, &dwRetVal);< p >上面這段代碼創建了一個Command對象并執行了一個SQL語句。如果我們要獲取數據，可以使用Recordset對象。例如：< pre >// 定義Recordset對象 IDBCreateCommand *pIDBCreateCommand = NULL; ICommandText *pICommandText = NULL; IUnknown *pIUnknown = NULL; hr = pIDBCreateSession->CreateSession(NULL, IID_IDBCreateCommand, (IUnknown**)&pIDBCreateCommand); hr = pIDBCreateCommand->CreateCommand(NULL, IID_IUnknown, (IUnknown**)&pIUnknown); hr = pIUnknown->QueryInterface(IID_ICommandText, (void**)&pICommandText); hr = pICommandText->SetCommandText(strSQL); hr = pICommandText->Execute(NULL, IID_IRowset, ¶ms, &dwRowsetRetVal, (IUnknown**)&pIRowset); hr = CoCreateInstance(CLSID_Recordset, NULL, CLSCTX_INPROC_SERVER, IID_Recodset, (void**)&pRecordset); hr = pRecordset->QueryInterface(IID_IRowsetRelease, (void**)&pIRowsetRelease); hr = pRecordset->Open(pIRowsetRelease, NULL, adOpenStatic, adLockOptimistic, NULL); while (! pRecordset->adoEOF) { // 錄取數據 }< p >上面這段代碼使用了Recordset對象來從數據庫中讀取數據。< p >在C語言中使用ADO連接Oracle數據庫非常方便。我們只需要使用Windows API來創建對象，然后使用這些對象來操作數據庫。< p >總結：C語言中使用ADO連接Oracle數據庫是非常方便的，我們可以使用Windows API來創建對象并操作數據庫。這些對象包括Connection、Command、Recordset等。