Obtaining external data from an Access 2000 .mdb database through the use C++ ADO commands

Question

Hello all,

I am trying to use the method outlined in this example to obtain data from an Access 2000 .mdb database and display that data in a C++ console application.

http://msdn.microsoft.com/en-us/library/cc811599.aspx

I am using the ADO example and the  Northwind Access Sample Database and I am using Visual C++ Express 2008 Edition with a Windows XP operating system

The code compiles but doesn't execute correctly. I recieve an "Unhandled Exception: _com_error at memory ..." error and the debugger directs me to the hr statement. Also, I had to add the ::CoInitialize(Null) and ::CoUnitialize commands to this example.

I am assuming that the .mdb file type isn't supported by this ADO method and that this method only supports the .accdb file type. Is that correct?

#include <fstream>
#include <cmath>
#include <complex>
#include <iostream>
#include <iomanip>
#include <vector>
#include <limits>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <fcntl.h>
#include <string.h>
#include <ctype.h>
#include <icrsint.h>

using namespace std;

#import <C:\\Program Files\\Common Files\\system\\ado\\msado15.dll> rename( "EOF", "AdoNSEOF")

_bstr_t bstrConnect = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\Program Files\\Microsoft Office\\Office\\Samples\\Northwind.mdb;";

HRESULT hr;

//inline void TESTHR(HRESULT hr) {if FAILED(hr) _com_issue_error(hr); }

int main()
{
	::CoInitialize(NULL);
	const char* DAM = "ADO";
	ADODB::_ConnectionPtr pConn("ADODB.Connection");
	hr = pConn->Open(bstrConnect, "admin", "", ADODB::adConnectUnspecified);
	if(SUCCEEDED(hr))
	{
		cout<<DAM<<": Successfully connected to database. Data source name:\n  "
			<<pConn->GetConnectionString()<<endl;

		// Prepare SQL query
		_bstr_t query = "SELECT Customers.[Company], Customers.[First Name] FROM Customers;";
		cout <<DAM<<": SQL query \n  "<<query<<endl;

		// Execute
		ADODB::_RecordsetPtr pRS("ADODB.Recordset");
		hr = pRS->Open(query,
			_variant_t((IDispatch *) pConn, true),
			ADODB::adOpenUnspecified,
			ADODB::adLockUnspecified,
			ADODB::adCmdText);
		if(SUCCEEDED(hr))
		{
			cout<<DAM<<": Retrieve schema info for the given result set: "<< endl;
			ADODB::Fields* pFields = NULL;
			hr = pRS->get_Fields(&pFields);
			if(SUCCEEDED(hr) && pFields && pFields->GetCount() > 0)
			{
				for(long nIndex=0; nIndex < pFields->GetCount(); nIndex++)
				{
					cout << " | "<<_bstr_t(pFields->GetItem(nIndex)->GetName());
				}
				cout << endl;
			}
			else
			{
				cout<<DAM<<": Error: Number of fields in the result is set to zero." << endl;
			}
			cout<<DAM<<": Fetch the actual data: " << endl;
			int rowCount = 0;
			while (!pRS->AdoNSEOF)
			{
				for(long nIndex=0; nIndex < pFields->GetCount(); nIndex++)
				{
					cout<<" | "<<_bstr_t(pFields->GetItem(nIndex)->GetValue());
				}
				cout<< endl;
				pRS->MoveNext();
				rowCount++;
			}
			cout<<DAM<<": Total Row Count:  " << rowCount << endl;
		}
		pRS->Close();
		pConn->Close();
		cout<<DAM<<": Cleanup Done" << endl;
	}
	else
	{
		cout<<DAM<<" : Unable to connect to data source: "<<bstrConnect<<endl;
	}
	::CoUninitialize();
	return 0;
}

Any help with this would be greatly appreciated.

Thanks
Matt

Answer 1

According to the documentation the office 12 runtime supports the mdb file format.

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