FIX: SQLOLEDB Returns No Data When Using AutoFetch Option with Fast Forward Cursors (303446)

MORE INFORMATION

Steps to Reproduce Behavior

1. Copy the sample code below into a new Microsoft Visual C++ console application and compile the code. You may need to change the data source name, user id, and password, so that these values refer to valid values for your SQL Server. This code assumes that a table has already been created in the Pubs database using the following syntax:

   create table BigVarchar(ID int, BigVar varchar(1000))
   insert into BigVarchar values(1, 'A123')
   					

2. Run the code, and notice that the m_bigVarchar variable is empty, although the m_ID variable is not.

Sample Code

#define DBINITCONSTANTS

#include "stdafx.h"

#include <stdio.h>
#include <windows.h>
#include <atlbase.h>
#include <iostream>

#include <comdef.h>
#include <oledb.h>
#include <oledberr.h>
#include <sqloledb.h>


#define num_rowProps 24

struct PData
{
	//status and value
	int m_ID_Status;
	int m_ID;
	int m_bigVarchar_Status;
	char m_bigVarchar[1001];
};


int main(int argc, char* argv[])
{


	HRESULT			hr = NULL;
	IUnknown *		pIUnknown = NULL;
	IUnknown*		pISession = NULL;
	IDBInitialize *		pIDBInitialize = NULL;
	IDBProperties*		pIDBProperties = NULL;
	IDBCreateSession*	pIDBCreateSession = NULL;
	IDBCreateCommand*	pIDBCreateCommand = NULL;
	ICommandText*		pICommandText = NULL;
	ICommandProperties*	pICommandProperties;
	IRowset*		pIRowset = NULL;
	DBPROPSET		dbPropSet;
	DBPROP			rowProp[num_rowProps];
	IAccessor*		pIAccessor = NULL;
	HACCESSOR		hAccessor;
	DBBINDING*		rgBindings;
	DBBINDSTATUS*		rgStatus;
	rgBindings		= new DBBINDING[2];

	CLSID			clsid;
	ULONG			i;


//	variables for fetching data
	ULONG				cRows;
	HROW				hRows[1];
	HROW*				rghRows = &hRows[0];
	LONG				cRowsAffected;




	hr = CoInitialize(NULL);

	if( FAILED(hr = CLSIDFromProgID(L"SQLOLEDB", &clsid) ) )
			return 0;

	hr = CoCreateInstance(clsid, NULL, CLSCTX_INPROC_SERVER,
		IID_IDBInitialize, (void**)&pIDBInitialize);

	const ULONG nProps = 5;
	DBPROP InitProperties[nProps];
	DBPROPSET rgInitPropSet[1];

	for (i = 0; i < nProps; i++)
	{
		VariantInit(&InitProperties[i].vValue);
		InitProperties[i].dwOptions = DBPROPOPTIONS_REQUIRED;
		InitProperties[i].colid = DB_NULLID;
	}

	//level of prompting that will be done to complete the
	//connection process
	InitProperties[0].dwPropertyID = DBPROP_INIT_PROMPT;
	InitProperties[0].vValue.vt = VT_I2;
	InitProperties[0].vValue.iVal = DBPROMPT_NOPROMPT;

	//datasource name
	InitProperties[1].dwPropertyID = DBPROP_INIT_DATASOURCE;
	InitProperties[1].vValue.vt = VT_BSTR;
	InitProperties[1].vValue.bstrVal = SysAllocString(OLESTR("YourServer"));

	//userid
	InitProperties[2].dwPropertyID = DBPROP_AUTH_USERID;
	InitProperties[2].vValue.vt = VT_BSTR;
	InitProperties[2].vValue.bstrVal = SysAllocString(OLESTR("sa"));

	//password
	InitProperties[3].dwPropertyID = DBPROP_AUTH_PASSWORD;
	InitProperties[3].vValue.vt = VT_BSTR;
	InitProperties[3].vValue.bstrVal = SysAllocString(OLESTR(""));

	//database
	InitProperties[4].dwPropertyID = DBPROP_INIT_CATALOG;
	InitProperties[4].vValue.vt = VT_BSTR;
	InitProperties[4].vValue.bstrVal = SysAllocString(OLESTR("Pubs"));


	//assign the property structures to the property set
	rgInitPropSet[0].guidPropertySet = DBPROPSET_DBINIT;
	rgInitPropSet[0].cProperties = nProps;
	rgInitPropSet[0].rgProperties = InitProperties;

	
	//set the properties
	hr = pIDBInitialize->QueryInterface(IID_IDBProperties, (void **)&pIDBProperties);
	hr = pIDBProperties->SetProperties(1, rgInitPropSet);
	pIDBProperties->Release();

	hr = pIDBInitialize->Initialize();
	if (FAILED(hr))
		return 0;


	// create a session and a command, set the command text
	hr = pIDBInitialize->QueryInterface(IID_IDBCreateSession, (void **)&pIDBCreateSession);
	
	hr = pIDBCreateSession->CreateSession(NULL, IID_IDBCreateCommand, (IUnknown**)&pIDBCreateCommand);

	pIDBCreateSession->Release();

	hr = pIDBCreateCommand->CreateCommand(NULL, IID_ICommandText, (IUnknown**)&pICommandText);
	hr = pICommandText->SetCommandText(DBGUID_DBSQL, L"Select * from pubs..bigvarchar");
	hr = pICommandText->QueryInterface(IID_ICommandProperties, (void **)&pICommandProperties);

	
	// set the command/rowset properties for a Fast Forward cursor
	for (i = 0; i < num_rowProps; i++)
	{
		VariantInit(&rowProp[i].vValue);
		rowProp[i].dwOptions = DBPROPOPTIONS_REQUIRED;
		rowProp[i].colid = DB_NULLID;
	}

	
	static struct
	{
	DBPROPID    m_PropId;
	BOOL    m_Val;
	}    
	crsProps[num_rowProps] =
        {
            {DBPROP_SERVERCURSOR,       true},
            {DBPROP_DEFERRED,           false},
            {DBPROP_IRowsetChange,      false},
            {DBPROP_IRowsetLocate,      false},
            {DBPROP_IRowsetScroll,      false},
            {DBPROP_IRowsetUpdate,      false},
            {DBPROP_BOOKMARKS,          false},
            {DBPROP_CANFETCHBACKWARDS,  false},
            {DBPROP_CANSCROLLBACKWARDS, false},
            {DBPROP_CANHOLDROWS,        false},
            {DBPROP_LITERALBOOKMARKS,   false},
            {DBPROP_OTHERINSERT,        true},
            {DBPROP_OTHERUPDATEDELETE,  true},
            {DBPROP_OWNINSERT,          true},
            {DBPROP_OWNUPDATEDELETE,    true},
            {DBPROP_QUICKRESTART,       false},
            {DBPROP_IRowsetResynch,     false},
            {DBPROP_CHANGEINSERTEDROWS, false},
            {DBPROP_SERVERDATAONINSERT, false},
            {DBPROP_UNIQUEROWS,         false},
            {DBPROP_IMMOBILEROWS,       false},
            {DBPROP_IMultipleResults,   false},
            {DBPROP_ABORTPRESERVE,      true},
            {DBPROP_COMMITPRESERVE,     true}
        };

	
	for (i = 0; i < num_rowProps; i++ )
	{
	VariantInit(&rowProp[i].vValue);
        	rowProp[i].dwOptions = DBPROPOPTIONS_REQUIRED;
        	rowProp[i].colid = DB_NULLID;
        	rowProp[i].dwPropertyID = crsProps[i].m_PropId;
        	rowProp[i].vValue.vt = VT_BOOL;
        	rowProp[i].vValue.boolVal = crsProps[i].m_Val ? VARIANT_TRUE : VARIANT_FALSE;
	}


	dbPropSet.rgProperties       = rowProp;
	dbPropSet.cProperties        = num_rowProps;
	dbPropSet.guidPropertySet    = DBPROPSET_ROWSET;	
	hr = pICommandProperties->SetProperties(1, &dbPropSet);
  
	pICommandProperties->Release();
	pICommandProperties = NULL;


	// set the provider-specific AutoFetch property
	DBPROP            rowProp2[1];
	DBPROPSET         rgPropSet2;
	rgPropSet2.guidPropertySet = DBPROPSET_SQLSERVERROWSET;
	rgPropSet2.cProperties = 1;
	rgPropSet2.rgProperties = rowProp2;

	VariantInit(&rowProp2[0].vValue);
	rowProp2[0].dwOptions = DBPROPOPTIONS_REQUIRED;
	rowProp2[0].colid = DB_NULLID;
	rowProp2[0].dwPropertyID = SSPROP_CURSORAUTOFETCH;
	rowProp2[0].vValue.vt = VT_BOOL;
	rowProp2[0].vValue.boolVal = VARIANT_TRUE;

	hr = pICommandText->QueryInterface(IID_ICommandProperties, (void **)&pICommandProperties);
	hr = pICommandProperties->SetProperties(1, &rgPropSet2);
	pICommandProperties->Release();


	// set up the binding structures for fetching data
	rgBindings = new DBBINDING[2];
	rgStatus = new DBBINDSTATUS[2];

	PData * pdata = new PData;
	memset( pdata, 0, sizeof(PData) );
	
	// binding for ID field
	rgBindings[0].iOrdinal = 1;
	rgBindings[0].pTypeInfo = NULL;
	rgBindings[0].pObject = NULL;
	rgBindings[0].pBindExt = NULL;
	rgBindings[0].dwMemOwner = DBMEMOWNER_CLIENTOWNED;
	rgBindings[0].eParamIO = DBPARAMIO_OUTPUT;
	rgBindings[0].dwFlags = 0;

	rgBindings[0].dwPart = DBPART_VALUE | DBPART_STATUS;
	rgBindings[0].obStatus = offsetof(PData, m_ID_Status);
	rgBindings[0].obLength = 0;
	rgBindings[0].obValue = offsetof(PData, m_ID);
	rgBindings[0].cbMaxLen = 4;
	rgBindings[0].wType = DBTYPE_I8;
	rgBindings[0].bPrecision = 0;
	rgBindings[0].bScale = 0;


	// binding for BigVar field
	rgBindings[1].iOrdinal = 2;
	rgBindings[1].pTypeInfo = NULL;
	rgBindings[1].pObject = NULL;
	rgBindings[1].pBindExt = NULL;
	rgBindings[1].dwMemOwner = DBMEMOWNER_CLIENTOWNED;
	rgBindings[1].eParamIO = DBPARAMIO_OUTPUT;
	rgBindings[1].dwFlags = 0;

	rgBindings[1].dwPart = DBPART_VALUE | DBPART_STATUS;
	rgBindings[1].obStatus = offsetof(PData, m_bigVarchar_Status); 
	rgBindings[1].obLength = 0;
	rgBindings[1].obValue = offsetof(PData, m_bigVarchar);
	rgBindings[1].cbMaxLen = 1001;
	rgBindings[1].wType = DBTYPE_STR;
	rgBindings[1].bPrecision = 0;
	rgBindings[1].bScale = 0;




	// execute the command and create an Accessor
	hr = pICommandText->Execute(NULL,
									IID_IRowset,
									NULL,
									&cRowsAffected,
									(IUnknown**)&pIRowset);


	hr = pIRowset->QueryInterface(IID_IAccessor, (void**)&pIAccessor);
	hr = pIAccessor->CreateAccessor(DBACCESSOR_ROWDATA,
									2,
									rgBindings,
									sizeof(PData),
									&hAccessor,
									rgStatus);

	// fetch the data
	hr = pIRowset->GetNextRows(NULL, 0, 1, &cRows, &rghRows);
	hr = pIRowset->GetData(rghRows[0], hAccessor, (void*)pdata);

	printf("Returned HRESULT:  \t%#X\n", hr);
	printf("Returned values:  m_ID = %i, m_bigVarchar = %s\n", pdata->m_ID, pdata->m_bigVarchar);
	printf("\nHit any key to continue...");
	getchar();


	hr = pIRowset->ReleaseRows(1, hRows, NULL, NULL, NULL);


	pIRowset->Release();
	pIAccessor->ReleaseAccessor(hAccessor,NULL);
	pIAccessor->Release();

	pICommandText->Release();


	return 0;
}