employees.cpp

EVC下OLEDB方法编写的数据库源代码

	IRowsetIndex		*pIRowsetIndex		= NULL;				// Provider Interface Pointer
	IAccessor			*pIAccessor			= NULL;				// Provider Interface Pointer
	ILockBytes			*pILockBytes		= NULL;				// Provider Interface Pointer
	IColumnsInfo		*pIColumnsInfo		= NULL;				// Provider Interface Pointer
	HACCESSOR			hAccessor			= DB_NULL_HACCESSOR;// Accessor handle

	WCHAR*				pwszEmployees[]		=	{						// Employee info Column names
													L"EmployeeID",
													L"Address",
													L"City",   
													L"Region", 
													L"PostalCode",
													L"Country", 
													L"HomePhone",
													L"Photo"	
												};
	
	VariantInit(&rowsetprop[0].vValue);

	// Validate IDBCreateSession interface
	//
	if (NULL == m_pIDBCreateSession)
	{
		hr = E_POINTER;
		goto Exit;
	}

    // Create a session object 
    //
    hr = m_pIDBCreateSession->CreateSession(NULL, IID_IOpenRowset, (IUnknown**) &pIOpenRowset);
    if(FAILED(hr))
    {
        goto Exit;
    }

	// Set up information necessary to open a table 
	// using an index and have the ability to seek.
	//
	TableID.eKind			= DBKIND_NAME;
	TableID.uName.pwszName	= (WCHAR*)TABLE_EMPLOYEE;

	IndexID.eKind			= DBKIND_NAME;
	IndexID.uName.pwszName	= L"PK_Employees";

	// Request ability to use IRowsetChange interface
	// 
	rowsetpropset[0].cProperties	= 1;
	rowsetpropset[0].guidPropertySet= DBPROPSET_ROWSET;
	rowsetpropset[0].rgProperties	= rowsetprop;

	rowsetprop[0].dwPropertyID		= DBPROP_IRowsetIndex;
	rowsetprop[0].dwOptions			= DBPROPOPTIONS_REQUIRED;
	rowsetprop[0].colid				= DB_NULLID;
	rowsetprop[0].vValue.vt			= VT_BOOL;
	rowsetprop[0].vValue.boolVal	= VARIANT_TRUE;

	// Open the table using the index
	//
	hr = pIOpenRowset->OpenRowset(	NULL,
									&TableID,
									&IndexID,
									IID_IRowsetIndex,
									sizeof(rowsetpropset)/sizeof(rowsetpropset[0]),
									rowsetpropset,
									(IUnknown**) &pIRowsetIndex);
	if(FAILED(hr))
	{
		goto Exit;
	}

    // Get IRowset interface
	//
	hr = pIRowsetIndex->QueryInterface(IID_IRowset, (void**) &pIRowset);
	if(FAILED(hr))
	{
		goto Exit;
	}

    // Get IColumnsInfo interface
	//
    hr = pIRowset->QueryInterface(IID_IColumnsInfo, (void **)&pIColumnsInfo);
	if(FAILED(hr))
	{
		goto Exit;
	}

	// Get the column metadata 
	//
    hr = pIColumnsInfo->GetColumnInfo(&ulNumCols, &pDBColumnInfo, &pStringsBuffer);
	if(FAILED(hr) || 0 == ulNumCols)
	{
		goto Exit;
	}

    // Create a DBBINDING array.
	//
	dwBindingSize = sizeof(pwszEmployees)/sizeof(pwszEmployees[0]);
	prgBinding = (DBBINDING*)CoTaskMemAlloc(sizeof(DBBINDING)*dwBindingSize);
	if (NULL == prgBinding)
	{
		hr = E_OUTOFMEMORY;
		goto Exit;
	}

	// Set initial offset for binding position
	//
	dwOffset = 0;

	// Prepare structures to create the accessor
	//
    for (dwIndex = 0; dwIndex < dwBindingSize; ++dwIndex)
    {
		if (!GetColumnOrdinal(pDBColumnInfo, ulNumCols, pwszEmployees[dwIndex], &dwOrdinal))
		{
			hr = E_FAIL;
			goto Exit;
		}

		// Prepare structures to create the accessor
		//
		prgBinding[dwIndex].iOrdinal	= dwOrdinal;
		prgBinding[dwIndex].dwPart		= DBPART_VALUE | DBPART_STATUS | DBPART_LENGTH;
		prgBinding[dwIndex].obLength	= dwOffset;                                     
		prgBinding[dwIndex].obStatus	= prgBinding[dwIndex].obLength + sizeof(ULONG);  
		prgBinding[dwIndex].obValue		= prgBinding[dwIndex].obStatus + sizeof(DBSTATUS);
		prgBinding[dwIndex].pTypeInfo	= NULL;
		prgBinding[dwIndex].pBindExt	= NULL;
		prgBinding[dwIndex].dwMemOwner	= DBMEMOWNER_CLIENTOWNED;
		prgBinding[dwIndex].dwFlags		= 0;
		prgBinding[dwIndex].bPrecision	= pDBColumnInfo[dwOrdinal].bPrecision;
		prgBinding[dwIndex].bScale		= pDBColumnInfo[dwOrdinal].bScale;

		switch(pDBColumnInfo[dwOrdinal].wType)
		{
		case DBTYPE_BYTES:		// Column "Photo" binding (BLOB) 
			// Set up the DBOBJECT structure.
			//
			dbObject.dwFlags = STGM_READ;
			dbObject.iid	 = IID_ILockBytes;

			prgBinding[dwIndex].pObject		= &dbObject;
			prgBinding[dwIndex].cbMaxLen	= sizeof(IUnknown*);
			prgBinding[dwIndex].wType		= DBTYPE_IUNKNOWN;
			break;

		case DBTYPE_WSTR:
			prgBinding[dwIndex].pObject		= NULL;
			prgBinding[dwIndex].wType		= pDBColumnInfo[dwOrdinal].wType;
			prgBinding[dwIndex].cbMaxLen	= sizeof(WCHAR)*(pDBColumnInfo[dwOrdinal].ulColumnSize + 1);	// Extra buffer for null terminator 
			break;

		default:
			prgBinding[dwIndex].pObject		= NULL;
			prgBinding[dwIndex].wType		= pDBColumnInfo[dwOrdinal].wType;
			prgBinding[dwIndex].cbMaxLen	= pDBColumnInfo[dwOrdinal].ulColumnSize; 
			break;
		}

		// Calculate new offset
		// 
		dwOffset = prgBinding[dwIndex].obValue + prgBinding[dwIndex].cbMaxLen;

		// Properly align the offset
		//
		dwOffset = ROUND_UP(dwOffset, COLUMN_ALIGNVAL);
	}

	// Get IAccessor interface
	//
	hr = pIRowset->QueryInterface(IID_IAccessor, (void**)&pIAccessor);
	if(FAILED(hr))
	{
		goto Exit;
	}

    // Create accessor.
	//
    hr = pIAccessor->CreateAccessor(DBACCESSOR_ROWDATA, 
									dwBindingSize, 
									prgBinding,
									0,
									&hAccessor,
									NULL);
    if(FAILED(hr))
    {
        goto Exit;
    }

	// Allocate data buffer for seek and retrieve operation.
	//
	pData = (BYTE*)CoTaskMemAlloc(dwOffset);
	if (NULL == pData)
	{
		hr = E_OUTOFMEMORY;
		goto Exit;
	}

    // Set data buffer to zero
    //
    memset(pData, 0, dwOffset);

    // Set data buffer for seek operation
    //
	*(ULONG*)(pData+prgBinding[0].obLength)		= 4;
	*(DBSTATUS*)(pData+prgBinding[0].obStatus)	= DBSTATUS_S_OK;
	*(int*)(pData+prgBinding[0].obValue)		= dwEmployeeID;

 	// Position at a key value within the current range 
	//
	hr = pIRowsetIndex->Seek(hAccessor, 1, pData, DBSEEK_FIRSTEQ);
	if(FAILED(hr))
	{
		goto Exit;	
	}

    // Retrieve a row handle for the row resulting from the seek
    //
    hr = pIRowset->GetNextRows(DB_NULL_HCHAPTER, 0, 1, &cRowsObtained, &prghRows);
	if(FAILED(hr))
	{
		goto Exit;	
	}

	if (DB_S_ENDOFROWSET != hr)
	{
		// Fetch actual data
		//
		hr = pIRowset->GetData(prghRows[0], hAccessor, pData);
		if (FAILED(hr))
		{
			goto Exit;
		}

		// Clear employee info on the dialog
		//
		ClearEmployeeInfo();

		// Update dialog
		// If return a null value or status is not OK, ignore the contents of the value and length parts of the buffer.
		//
    	if (DBSTATUS_S_ISNULL != *(DBSTATUS *)(pData+prgBinding[0].obStatus) && 
            DBSTATUS_S_OK == *(DBSTATUS *)(pData+prgBinding[0].obStatus))
	    {
		    SetDlgItemInt(m_hWndEmployees,  IDC_EDIT_EMPLOYEE_ID, *(LONG*)(pData+prgBinding[0].obValue), 0);
        }

		if (DBSTATUS_S_ISNULL != *(DBSTATUS *)(pData+prgBinding[1].obStatus) &&
            DBSTATUS_S_OK == *(DBSTATUS *)(pData+prgBinding[1].obStatus))
		{
			SetDlgItemText(m_hWndEmployees, IDC_EDIT_ADDRESS, (WCHAR*)(pData+prgBinding[1].obValue));
		}

		if (DBSTATUS_S_ISNULL != *(DBSTATUS *)(pData+prgBinding[2].obStatus) &&
            DBSTATUS_S_OK == *(DBSTATUS *)(pData+prgBinding[2].obStatus))
		{
			SetDlgItemText(m_hWndEmployees, IDC_EDIT_CITY, (WCHAR*)(pData+prgBinding[2].obValue));
		}

		if (DBSTATUS_S_ISNULL != *(DBSTATUS *)(pData+prgBinding[3].obStatus) &&
            DBSTATUS_S_OK == *(DBSTATUS *)(pData+prgBinding[3].obStatus))
		{
			SetDlgItemText(m_hWndEmployees, IDC_EDIT_REGION, (WCHAR*)(pData+prgBinding[3].obValue));
		}

		if (DBSTATUS_S_ISNULL != *(DBSTATUS *)(pData+prgBinding[4].obStatus) &&
            DBSTATUS_S_OK == *(DBSTATUS *)(pData+prgBinding[4].obStatus))
		{
			SetDlgItemText(m_hWndEmployees, IDC_EDIT_POSTAL_CODE, (WCHAR*)(pData+prgBinding[4].obValue));
		}

		if (DBSTATUS_S_ISNULL != *(DBSTATUS *)(pData+prgBinding[5].obStatus) &&
            DBSTATUS_S_OK == *(DBSTATUS *)(pData+prgBinding[5].obStatus))
		{
			SetDlgItemText(m_hWndEmployees, IDC_EDIT_COUNTRY, (WCHAR*)(pData+prgBinding[5].obValue));
		}

		if (DBSTATUS_S_ISNULL != *(DBSTATUS *)(pData+prgBinding[6].obStatus) &&
            DBSTATUS_S_OK == *(DBSTATUS *)(pData+prgBinding[6].obStatus))
		{
			SetDlgItemText(m_hWndEmployees, IDC_EDIT_HOME_PHONE, (WCHAR*)(pData+prgBinding[6].obValue));
		}

		// Update employee photo
		// 
		if (DBSTATUS_S_ISNULL != *(DBSTATUS *)(pData+prgBinding[7].obStatus) &&
            DBSTATUS_S_OK == *(DBSTATUS *)(pData+prgBinding[7].obStatus))
        {
    		pILockBytes = (*(ILockBytes**) (pData + prgBinding[7].obValue));
	    	LoadEmployeePhoto(pILockBytes);
        }
	}

	// Release the rowset.
	//
	pIRowset->ReleaseRows(1, prghRows, NULL, NULL, NULL);

Exit:
    // Clear Variants
    //
	VariantClear(&rowsetprop[0].vValue);

    // Free allocated memory for row handles.
    //
	if (prghRows)
	{
        CoTaskMemFree(prghRows);
        prghRows = NULL;
	}

    // Free allocated DBBinding memory
    //
    if (prgBinding)
    {
        CoTaskMemFree(prgBinding);
        prgBinding = NULL;
    }

    // Free allocated column info memory
    //
    if (pDBColumnInfo)
    {
        CoTaskMemFree(pDBColumnInfo);
        pDBColumnInfo = NULL;
    }
	
	// Free allocated column string values buffer
    //
    if (pStringsBuffer)
    {
        CoTaskMemFree(pStringsBuffer);
        pStringsBuffer = NULL;
    }

    // Free data record buffer
    //
	if (pData)
	{
        CoTaskMemFree(pData);
		pData = NULL;
	}

	// Release interfaces
	//
	if(pILockBytes)
	{
		pILockBytes->Release();
	}

	if(pIAccessor)
	{
		pIAccessor->ReleaseAccessor(hAccessor, NULL); 
		pIAccessor->Release();
	}

	if (pIColumnsInfo)
	{
		pIColumnsInfo->Release();
	}

	if(pIRowset)
	{
		pIRowset->Release();
	}

	if (pIRowsetIndex)
	{
		pIRowsetIndex->Release();
	}

	if(pIOpenRowset)
	{
		pIOpenRowset->Release();
	}

	return hr;
}

////////////////////////////////////////////////////////////////////////////////
// Function: LoadEmployeePhoto()
//
// Description: Load employee photo from database.
//
// Returns: NOERROR if succesfull
//
// Notes: This sample only display 24 bit bitmap
//
////////////////////////////////////////////////////////////////////////////////
HRESULT Employees::LoadEmployeePhoto(ILockBytes* pILockBytes)
{
	HRESULT				hr = NOERROR;
	ULONG				ulRead;
	ULARGE_INTEGER		ulStart;
	BITMAPFILEHEADER	bmpFileHeader;
	BITMAPINFO			bmpInfo;
	BYTE				*pPhotoBits;
	HDC					hDC;

	if (m_hBitmap)
	{
		// Delete bitmap object, release the device contexts, 
		//
		DeleteObject(m_hBitmap);
		m_hBitmap = NULL;
	}

	// Validate ILockBytes interface 
	//
	if (NULL == pILockBytes)
	{
		return hr;
	}

	// Read Bitmap file header
	//
	ulRead = 0;
	ulStart.QuadPart = 0;
	hr = pILockBytes->ReadAt(ulStart, &bmpFileHeader, sizeof(BITMAPFILEHEADER), &ulRead);
	if(FAILED(hr) || sizeof(BITMAPFILEHEADER) != ulRead) 
	{
		return hr;
	}

	// Read Bitmap info header
	//
	ulStart.QuadPart += ulRead;
	ulRead = 0;
	hr = pILockBytes->ReadAt(ulStart, &bmpInfo, sizeof(BITMAPINFOHEADER), &ulRead);
	if(FAILED(hr) || sizeof(BITMAPINFOHEADER) != ulRead) 
	{
		return hr;
	}

	// THIS SAMPLE ONLY SUPPORT 24 BIT BITMAP
	//
	if (24 != bmpInfo.bmiHeader.biBitCount)
	{
		return hr;
	}

	// Retrieve the device context handle
	//
	hDC = GetDC(m_hWndEmployees);

	// Creates a device-independent bitmap (DIB) with bitmap info
	//
	m_hBitmap = CreateDIBSection(	hDC,
								&bmpInfo, 
								DIB_RGB_COLORS, 
								(void **)&pPhotoBits, 
								NULL, 
								0);

	// Read bitmap bits
	//
	ulStart.QuadPart += ulRead;
	ulRead = 0;
	hr = pILockBytes->ReadAt(ulStart, pPhotoBits, bmpInfo.bmiHeader.biSizeImage, &ulRead);
	if(FAILED(hr) || bmpInfo.bmiHeader.biSizeImage != ulRead) 
	{
		// Delete bitmap object, release the device contexts, 
		//
		DeleteObject(m_hBitmap);
		m_hBitmap = NULL;
	}

	ReleaseDC(m_hWndEmployees, hDC);

	return hr;
}

////////////////////////////////////////////////////////////////////////////////
// Function: ShowEmployeePhoto()