Teach yourself Database Programming with Visual C++ 6 in 21 days -- Appendix E-Using ADO via the OLE DB SDK



Teach Yourself Database Programming with Visual C++ 6 in 21 days







Appendix E
Using ADO via the OLE DB SDK


To use ADO in your C++ applications, you can use the ADO header
files and import library from the OLE DB SDK. You include the
ADO header files (adoid.h and adoint.h) in your source, and add
the ADO import library adoid.lib to your linker input. This enables
you to create instances of the ADO objects and access their member
functions. The code listings that follow show the changes you
would need to make to a typical MFC application to use ADO via
the OLE DB SDK. A sample MFC application called ADOSDK is on the
CD.


Listing E.1  Additions to StdAfx.h



1: #include <adoid.h>
2: #include <adoint.h>
3: #include <comdef.h>





Listing E.2   Additions to the Document Header File




1: class CADOSDKDoc : public CDocument
2: {
3: protected: // create from serialization only
4: CADOSDKDoc();
5: DECLARE_DYNCREATE(CADOSDKDoc)
6:
7: // Attributes
8: public:
9: ADOConnection* m_piConnection;
10: BOOL m_ConnectionOpen;




Lines 9 and 10 are the new lines you need to add. The other lines
should be there already.


Listing E.3  Additions to the Document Constructor




1: CADOSDKDoc::CADOSDKDoc()
2: {
3: m_piConnection = NULL;
4: m_ConnectionOpen = FALSE;
5: }




Lines 4 and 5 are the new lines you need to add. The other lines
should be there already.


Listing E.4  Additions to the ONNEWDOCUMENT Function




1: BOOL CADOSDKDoc::OnNewDocument()
2: {
3: if (!CDocument::OnNewDocument())
4: return FALSE;
5:
6: HRESULT hr;
7:
8: hr = CoCreateInstance(CLSID_CADOConnection, NULL,
9: CLSCTX_INPROC_SERVER, IID_IADOConnection,
10: (LPVOID *)&m_piConnection);
11: if (!FAILED(hr))
12: {
13: hr = m_piConnection->Open(bstr_t(
14: _ L"Provider=Microsoft.Jet.OLEDB.3.51;Data
Source=c:\\tysdbvc\\vcdb.mdb;"),
15: NULL, NULL);
16: if (!FAILED(hr))
17: {
18: m_ConnectionOpen = TRUE;
19: }
21: }
22:
23: return TRUE;
24: }




Lines 6-21 are the new lines you need to add. The other lines
should be there already. Line 14 will change, depending on the
location of the file.


Listing E.5  Additions to the ONCLOSEDOCUMENT Function




1: void CADOSDKDoc::OnCloseDocument()
2: {
3: if (m_ConnectionOpen)
4: {
5: m_piConnection->Close();
6: m_ConnectionOpen = FALSE;
7: }
8: if (m_piConnection)
9: {
10: m_piConnection->Release();
11: }
12:
13: CDocument::OnCloseDocument();
14: }




Lines 3-11 are the new lines you need to add. The other lines
should be there already from ClassWizard.


Listing E.6  Additions to the ONRBUTTONDOWN Function




1: void CADOSDKView::OnRButtonDown(UINT nFlags, CPoint point)
2: {
3: CADOSDKDoc * pDoc = GetDocument();
4: HRESULT hr;
5: ADORecordset * pRs = NULL;
6: short sEOF;
7: _variant_t vLastName;
8:
9: if (pDoc->m_ConnectionOpen)
10: {
11: hr = pDoc->m_piConnection->Execute(
12: _bstr_t(L"SELECT * FROM Customers"),
13: &(_variant_t(0L)),
14: adCmdText,
15: &pRs);
16:
17: if (SUCCEEDED(hr))
18: {
19: pRs->get_EOF(&sEOF);
20: while (!sEOF)
21: {
22: hr = pRs->get_Collect(_variant_t(L"CustLastName"),
&vLastName);
23: if (SUCCEEDED(hr))
24: {
25: TRACE("Last Name:%s.\n", (LPCTSTR) (_bstr_t) vLastName);
26: }
27: pRs->MoveNext();
28: pRs->get_EOF(&sEOF);
29: }
30: pRs->Close();
31: pRs->Release();
32: }
33:
34: }
35:
36: CView::OnRButtonDown(nFlags, point);
37: }




Lines 3-34 are the new lines you need to add. The other lines
should be there already from ClassWizard.







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