如何： C + + 樣本的 ADO 資料錄集 XML 保存性

// 1. ADO Recordset <-> external xml file
// 2. ADO Recordset <-> ADO IStream Object
// 3. ADO Recordset <-> DOM Document

#import "C:\Program files\Common Files\System\Ado\msado15.dll" rename_namespace("MSXML")  rename("EOF", "ADOEOF")

#import "c:\winnt\system32\msxml.dll" 
using namespace MSXML;

#include "stdio.h"
#include "io.h"
void dump_error(_com_error &e) ; //exception handling

void main()
{
HRESULT hr;
CoInitialize(NULL);

try
{
//open the connection, get the reocrdset ready
_ConnectionPtr pConn;
_RecordsetPtr pRs;

hr = pConn.CreateInstance(__uuidof(Connection));
hr = pRs.CreateInstance(__uuidof(Recordset));

pConn->CursorLocation = adUseClient;
_bstr_t strConn("Provider=sqloledb;Data Source=juliaj01;Initial Catalog=pubs;User Id=<username>;Password=<strong password>;");
hr = pConn->Open(strConn, "<username>", "<strong password>", adConnectUnspecified);
hr = pRs->Open("SELECT * from authors", pConn.GetInterfacePtr(), adOpenForwardOnly, adLockReadOnly, adCmdText);

//preparation to save RS as xml file, 
struct _finddata_t xml_file;
long hFile;
if( (hFile = _findfirst("authors.xml", &xml_file )) != -1L)
{
DeleteFile("authors.xml"); //if the file exists, delete it
}

// 1. Persist it to an external xml file by calling Save with file name and adPersistXML
hr = pRs->Save("authors.xml", adPersistXML);

// 2. Persist it to ADO IStream Object
_StreamPtrpStream ; //declare one first
pStream.CreateInstance(__uuidof(Stream)); //create it after
hr = pRs->Save(pStream.GetInterfacePtr(), adPersistXML);    //old trick, call Save 

// 3. Persist it to DOM Document
IXMLDOMDocumentPtr pXMLDOMDoc; 
pXMLDOMDoc.CreateInstance(__uuidof(DOMDocument));
hr = pRs->Save(pXMLDOMDoc.GetInterfacePtr(), adPersistXML);
// if you want to check out the content call printf(pXMLDOMDoc->Getxml());

//Recycle the Recordset object
hr = pRs->Close();

// 4. load the recordset back from the file by calling Open with MSPersist provider and adCmdFile. 
// the Recordset will be a ReadOnly, Forwardly only
hr = pRs->Open("authors.xml","Provider=MSPersist;",adOpenForwardOnly,adLockReadOnly,adCmdFile);
    hr = pRs->Close();

// 5.  Load from IStream object, call Open, first param is pStream.GetInterfacePtr()

//  Set the steam object position to the beginning of the stream:
pStream->Position = 0;

//  call Open,  passing in vtMissing for connection string, see Q245485 for details
hr = pRs->Open(pStream.GetInterfacePtr(),vtMissing, adOpenForwardOnly,adLockReadOnly,adCmdFile);

hr = pRs->Close();

// 6 .Load from DOM Document, call Open, first param is pXMLDOMDoc.GetInterfacePtr() and 
// pass in vtMissing for connection string, see Q245485

hr = pRs->Open(pXMLDOMDoc.GetInterfacePtr(), vtMissing, adOpenForwardOnly, adLockReadOnly, adCmdFile);

hr = pRs->Close();



//Don't forget to clean up the stream object
hr = pStream->Close();

}
catch(_com_error &e)
{
dump_error(e);
}
}

void dump_error(_com_error &e)
{
_bstr_t bstrSource(e.Source());
_bstr_t bstrDescription(e.Description());

// Print Com errors.  
printf("Error\n");
printf("\tCode = %08lx\n", e.Error());
printf("\tCode meaning = %s", e.ErrorMessage());
printf("\tSource = %s\n", (LPCSTR) bstrSource);
printf("\tDescription = %s\n", (LPCSTR) bstrDescription);

}