ISequentialStream を使用した FILESTREAM 列からのデータの取得 (OLE DB)
適用対象: 
SQL Server Azure SQL データベース Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW)
このサンプルでは、ICommandText インターフェイス内で ISequentialStream インターフェイスを使用して、FILESTREAM 列から単一のレコードを取得する方法を示します。
FILESTREAM 機能の詳細については、「OLE DB Driver for SQL Server の FILESTREAM サポート」を参照してください。
例
INCLUDE 環境変数に、msoledbsql.h が保存されているディレクトリが含まれていることを確認します。
次のいずれかのサンプルを使用して、このサンプルで読み取るテーブルを作成します。
1 つ目のコード リストをコピーし、ISSHelper.h という名前のファイルに貼り付けます。
2 つ目のコード リストをコピーし、ISSHelper.cpp という名前のファイルに貼り付けます。
3 つ目のコード リストをコピーし、ICommandDownload.cpp という名前のファイルに貼り付けます。
ICommandDownload.cpp、ISSHelper.cpp、ole32.lib、oleaut32.lib をコンパイルします。
このサンプルを実行する際は、サーバー名 (または server\instance_name) を渡す必要があります。
// ISSHelper.h: interface for the CISSHelper class.
#if !defined(AFX_ISSHELPER_H__7B88E5F3_263F_11D2_9D1F_00C04F96B8B2__INCLUDED_)
#define AFX_ISSHELPER_H__7B88E5F3_263F_11D2_9D1F_00C04F96B8B2__INCLUDED_
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
class CISSHelper : public ISequentialStream {
public:
// Constructor/destructor.
CISSHelper(__int64 i64LobBytes);
virtual ~CISSHelper();
// Helper function to clean up memory.
virtual void Clear();
// ISequentialStream interface implementation.
STDMETHODIMP_(ULONG)AddRef(void);
STDMETHODIMP_(ULONG)Release(void);
STDMETHODIMP QueryInterface(REFIID riid, LPVOID *ppv);
STDMETHODIMP Read(
/* [out] */ void __RPC_FAR *pv,
/* [in] */ ULONG cb,
/* [out] */ ULONG __RPC_FAR *pcbRead);
STDMETHODIMP Write(
/* [in] */ const void __RPC_FAR *pv,
/* [in] */ ULONG cb,
/* [out] */ ULONG __RPC_FAR *pcbWritten);
public:
void * m_pBuffer; // Buffer
ULONG m_ulLength; // Total buffer size.
ULONG m_ulStatus; // Column status.
__int64 m_i64BytesUploaded;
__int64 m_i64LastPrintUploaded;
__int64 m_i64ThreshHold;
DWORD m_dwStartTick;
DWORD m_dwParamOrdinal;
private:
ULONG m_cRef; // Reference count (not used).
ULONG m_iReadPos; // Current index position for reading from the buffer.
ULONG m_iWritePos; // Current index position for writing to the buffer.
};
#endif // !defined(AFX_ISSHELPER_H__7B88E5F3_263F_11D2_9D1F_00C04F96B8B2__INCLUDED_)
// ISSHelper.cpp: implementation of the CISSHelper class.
#pragma once
#define WIN32_LEAN_AND_MEAN// Exclude rarely-used stuff from Windows headers
#include <windows.h>
#include <stdio.h>// printf(...)
#include <stddef.h>// offsetof(...)
#include <conio.h>// _getch()
#include <oledb.h>// OLEDB
#include <oledberr.h>// OLEDB
#include <objbase.h>// CoInitializeEx()
#include <msdasc.h>// IDataInitialize
#include <msdadc.h>// OLEDB conversion library header.
#include <msdaguid.h>// OLEDB conversion library guids.
#include <tchar.h>
// TODO: reference additional headers your program requires here
#define _MSOLEDBSQL_OLEDB_ 1
#include <msoledbsql.h>
#include "ISSHelper.h"
#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUm_NEW
#endif
// Implementation of ISequentialStream interface
CISSHelper::CISSHelper(__int64 i64LobBytes) {
m_cRef= 0;
m_pBuffer= NULL;
m_ulLength= 0;
m_ulStatus = DBSTATUS_S_OK;
m_iReadPos= 0;
m_iWritePos= 0;
m_i64ThreshHold = i64LobBytes;
m_i64BytesUploaded = 0;
m_i64LastPrintUploaded = 0;
m_dwStartTick = 0;
m_dwParamOrdinal = 0;
}
CISSHelper::~CISSHelper() {
Clear();
}
void CISSHelper::Clear() {
CoTaskMemFree( m_pBuffer );
m_cRef= 0;
m_pBuffer= NULL;
m_ulLength= 0;
m_ulStatus = DBSTATUS_S_OK;
m_iReadPos= 0;
m_iWritePos= 0;
}
ULONG CISSHelper::AddRef() {
return ++m_cRef;
}
ULONG CISSHelper::Release() {
return --m_cRef;
}
HRESULT CISSHelper::QueryInterface( REFIID riid, void** ppv ) {
*ppv = NULL;
if ( riid == IID_IUnknown ) *ppv = this;
if ( riid == IID_ISequentialStream ) *ppv = this;
if ( *ppv )
{
( (IUnknown*) *ppv )->AddRef();
return S_OK;
}
return E_NOINTERFACE;
}
HRESULT CISSHelper::Read( void *pv,ULONG cb, ULONG* pcbRead ) {
// Check parameters.
if ( pcbRead ) *pcbRead = 0;
if ( !pv ) return STG_E_INVALIDPOINTER;
if ( 0 == cb ) return S_OK;
// Cut out now if threshold is hit.
__int64 left = m_i64ThreshHold-m_i64BytesUploaded;
if (left < cb)
cb = (ULONG)left;
if (0 == m_dwStartTick)
m_dwStartTick = GetTickCount();
m_i64BytesUploaded += cb;
if (( m_i64BytesUploaded - m_i64LastPrintUploaded ) >= (1024*1024*4)) {
__int64 i64Elapsed = (__int64) GetTickCount()-m_dwStartTick;
// __int64 i64BytesPerSecond = m_i64BytesUploaded * 1000 / (i64Elapsed > 0 ) ? i64Elapsed : 1;
__int64 i64BytesPerSecond = m_i64BytesUploaded * 1000 / i64Elapsed > 0 ? i64Elapsed : 1;
printf("Param=%lu TotalBytes=%010I64u ElapsedMS=%010I64u BytesPerSec=%010I64u\n",
m_dwParamOrdinal, m_i64BytesUploaded, i64Elapsed, i64BytesPerSecond );
m_i64LastPrintUploaded = m_i64BytesUploaded;
}
if ( cb == left ) {
__int64 i64Elapsed = (__int64) GetTickCount()-m_dwStartTick;
// __int64 i64BytesPerSecond = m_i64BytesUploaded * 1000 / (i64Elapsed > 0 ) ? i64Elapsed : 1;
__int64 i64BytesPerSecond = m_i64BytesUploaded * 1000 / i64Elapsed > 0 ? i64Elapsed : 1;
printf("Last read:\nParam=%lu TotalBytes=%010I64u ElapsedMS=%010I64u BytesPerSec=%010I64u\n",
m_dwParamOrdinal, m_i64BytesUploaded, i64Elapsed, i64BytesPerSecond );
m_i64LastPrintUploaded = m_i64BytesUploaded;
}
*pcbRead = cb;
return S_OK;
}
HRESULT CISSHelper::Write( const void *pv, ULONG cb, ULONG* pcbWritten ) {
// Check parameters.
if ( !pv ) return STG_E_INVALIDPOINTER;
if ( pcbWritten ) *pcbWritten = 0;
if ( 0 == cb ) return S_OK;
// Enlarge the current buffer.
m_ulLength += cb;
// Grow internal buffer to new size.
m_pBuffer = CoTaskMemRealloc( m_pBuffer, m_ulLength );
// Check for out of memory situation.
if ( NULL == m_pBuffer ) {
Clear();
return E_OUTOFMEMORY;
}
// Copy callers memory to internal buffer and update write position.
memcpy( (void*)((BYTE*)m_pBuffer + m_iWritePos), pv, cb );
m_iWritePos += cb;
// Return bytes written to caller.
if ( pcbWritten ) *pcbWritten = cb;
return S_OK;
}
// ICommandDownload.cpp
#pragma once
#define WIN32_LEAN_AND_MEAN// Exclude rarely-used stuff from Windows headers
#include <windows.h>
#include <stdio.h>// printf(...)
#include <stddef.h>// offsetof(...)
#include <conio.h>// _getch()
#include <oledb.h>// OLEDB
#include <oledberr.h>// OLEDB
#include <objbase.h>// CoInitializeEx()
#include <msdasc.h>// IDataInitialize
#include <msdadc.h>// OLEDB conversion library header.
#include <msdaguid.h>// OLEDB conversion library guids.
#include <tchar.h>
// TODO: reference additional headers your program requires here
#define _MSOLEDBSQL_OLEDB_ 1
#include <msoledbsql.h>
#include "ISSHelper.h"
// Simple data record used by DumpRowset function.
#define MAX_DATA_LENGTH 8096
struct DATA_REC {
DWORD status;
DWORD length;
BYTE Data[MAX_DATA_LENGTH];
};
// Helper macros for COM/OLEDB.
#define SAFE_RELEASE(x) { if (x) { x->Release(); x = NULL; } }
#define SAFE_SYSFREE(bstr) { if (bstr) { ::SysFreeString(bstr); bstr = NULL; } }
#define CHECK_HR(hr,jump) { if ( FAILED(hr) ) goto jump; }
#define CHECK_HR_ERR(hr,jump) { if ( FAILED(hr) ) { DumpErrorRecords(); goto jump; } }
#define CLEAR_PROPS(x) { for ( int i = 0 ; i < x ; i++ ) VariantClear( &InitProperties[i].vValue ); }
#define SET_BSTR_PROP(index,propid,value) { \
InitProperties[index].dwOptions = DBPROPOPTIONS_REQUIRED; \
InitProperties[index].colid = DB_NULLID; \
InitProperties[index].dwStatus = DBPROPSTATUS_OK; \
InitProperties[index].dwPropertyID = propid; \
InitProperties[index].vValue.vt = VT_BSTR; \
InitProperties[index].vValue.bstrVal = SysAllocString(value); }
// Helper function for DumpErrorRecords() to convert a clisd to string representation of clsid.
LPWSTR CLSIDToString( CLSID* pclsid ) {
static WCHAR wszCLSID[1024];
if ( NULL == pclsid )
wcscpy_s(wszCLSID, 1024, L"(Null)");
else
::StringFromGUID2( *pclsid, (OLECHAR*)wszCLSID, sizeof(wszCLSID) );
return wszCLSID;
}
// Helper function to dump out OLE DB errors to console window.
HRESULT DumpErrorRecords() {
HRESULT hr = S_OK;
IErrorRecords* pIErrorRecords = NULL;
IErrorInfo* pIErrorInfo = NULL;
IErrorInfo* pIErrorInfoRecord = NULL;
BSTR bstrDescription = NULL;
BSTR bstrSource = NULL;
ULONG i;
ULONG cRecords = 0;
LCID lcid = 0;
ERRORINFO ErrorInfo;
// Get IErrorInfo pointer from OLE.
hr = ::GetErrorInfo( 0, &pIErrorInfo );
if ( FAILED(hr) ) {
printf( "No error records found.\n" );
goto DumpErrorRecordsExit;
}
// QI for IID_IErrorRecords.
hr = pIErrorInfo->QueryInterface( IID_IErrorRecords, (void**)&pIErrorRecords );
if ( FAILED(hr) ) {
printf( "pIErrorInfo->QueryInterface(IID_IErrorRecords) failed with hr=0x%08x.\n", hr );
goto DumpErrorRecordsExit;
}
// Get error record count.
hr = pIErrorRecords->GetRecordCount( &cRecords );
if ( FAILED(hr) ) {
printf( "pIErrorRecords->GetRecordCount() failed with hr=0x%08x.\n", hr );
goto DumpErrorRecordsExit;
}
// Get system LCID
lcid = GetSystemDefaultLCID();
//Loop through the error records.
for ( i = 0 ; i < cRecords ; i++ ) {
// Get pIErrorInfo from pIErrorRecords.
hr = pIErrorRecords->GetErrorInfo( i, lcid, &pIErrorInfoRecord );
if ( SUCCEEDED(hr) ) {
// Get error description and source.
hr = pIErrorInfoRecord->GetDescription( &bstrDescription );
hr = pIErrorInfoRecord->GetSource( &bstrSource );
// Retrieve the ErrorInfo structures.
hr = pIErrorRecords->GetBasicErrorInfo( i, &ErrorInfo );
// Dump out error.
printf( "\n" );
printf( "Dumping error record %lu of %lu:\n", i+1, cRecords );
printf( "--------------------------------------------------------------------------\n" );
printf( " Description = %S\n", bstrDescription );
printf( " Source = %S\n", bstrSource );
printf( " ERRORINFO.hrError = 0x%08x\n", ErrorInfo.hrError );
printf( " ERRORINFO.dwMinor = %lu\n",ErrorInfo.dwMinor );
printf( " ERRORINFO.clsid = %S\n",CLSIDToString( &ErrorInfo.clsid ) );
SAFE_RELEASE(pIErrorInfoRecord);
SAFE_SYSFREE(bstrDescription);
SAFE_SYSFREE(bstrSource);
}
}
DumpErrorRecordsExit:
SAFE_RELEASE(pIErrorInfoRecord);
SAFE_RELEASE(pIErrorRecords);
SAFE_RELEASE(pIErrorInfo);
SAFE_RELEASE(pIErrorInfo);
SAFE_SYSFREE(bstrDescription);
SAFE_SYSFREE(bstrSource);
return hr;
}
// Helper function to execute a sql command.
HRESULT ExecuteSQL( IDBCreateCommand* pIDBCreateCommand, LPCOLESTR pwszCommand ) {
HRESULT hr;
ICommandText* pICommandText = NULL;
hr = pIDBCreateCommand->CreateCommand( NULL, IID_ICommandText, (IUnknown**)&pICommandText );
CHECK_HR(hr,ExecuteSQLCleanup);
hr = pICommandText->SetCommandText( DBGUID_DBSQL, pwszCommand );
CHECK_HR(hr,ExecuteSQLCleanup);
hr = pICommandText->Execute( NULL, IID_NULL, NULL, NULL, NULL );
ExecuteSQLCleanup:
SAFE_RELEASE(pICommandText);
return hr;
}
HRESULT OpenSessionSSHelper( IDBProperties*pIDBProperties, IDBCreateCommand** ppIDBCreateCommand, wchar_t* szServer ) {
#define TOTAL_SS_PROPS 3
HRESULThr;
IDBInitialize*pIDBInitialize = NULL;
IDBCreateSession*pIDBCreateSession = NULL;
DBPROPInitProperties[TOTAL_SS_PROPS];
DBPROPSETInitPropSet;
if ( NULL == pIDBProperties )
return E_INVALIDARG;
if ( NULL == ppIDBCreateCommand )
return E_INVALIDARG;
// NULL our out param in case of failure.
*ppIDBCreateCommand = NULL;
// Hard coded this to point to local sql server, change as needed.
SET_BSTR_PROP( 0, DBPROP_INIT_DATASOURCE, szServer );
SET_BSTR_PROP( 1, DBPROP_INIT_CATALOG, L"master" );
SET_BSTR_PROP( 2, DBPROP_AUTH_INTEGRATED, L"SSPI" );
InitPropSet.guidPropertySet = DBPROPSET_DBINIT;
InitPropSet.cProperties = TOTAL_SS_PROPS;
InitPropSet.rgProperties = InitProperties;
// Set initialization properties.
hr = pIDBProperties->SetProperties( 1, &InitPropSet );
CHECK_HR(hr,OpenSessionSSHelperCleanup);
// Clean up allocated variants.
CLEAR_PROPS( TOTAL_SS_PROPS );
// Initialize the DataSource.
hr = pIDBProperties->QueryInterface( IID_IDBInitialize, (void**) &pIDBInitialize );
CHECK_HR(hr,OpenSessionSSHelperCleanup);
hr = pIDBInitialize->Initialize();
CHECK_HR(hr,OpenSessionSSHelperCleanup);
// QI for IID_IDBCreateSession and then create session.
hr = pIDBInitialize->QueryInterface( IID_IDBCreateSession, (void**) &pIDBCreateSession );
CHECK_HR(hr,OpenSessionSSHelperCleanup);
hr = pIDBCreateSession->CreateSession( NULL, IID_IDBCreateCommand, (IUnknown**)ppIDBCreateCommand );
OpenSessionSSHelperCleanup:
SAFE_RELEASE( pIDBInitialize );
SAFE_RELEASE( pIDBCreateSession );
return hr;
}
// Helper function to open a SS session.
HRESULT OpenSessionSS( IDBCreateCommand** ppIDBCreateCommand, wchar_t* szServer ) {
HRESULT hr;
IDBProperties * pIDBProperties = NULL;
// Null our out param in case we fail.
if ( NULL == ppIDBCreateCommand )
return E_INVALIDARG;
// Co-create MSOLEDBSQL.
hr = CoCreateInstance( MSOLEDBSQL_CLSID, NULL, CLSCTX_INPROC_SERVER, IID_IDBProperties,
(void **) &pIDBProperties );
CHECK_HR(hr,OpenSessionSSCleanup);
// Call helper to open session.
hr = OpenSessionSSHelper( pIDBProperties, ppIDBCreateCommand, szServer );
OpenSessionSSCleanup:
SAFE_RELEASE( pIDBProperties );
return hr;
}
void wmain(int argc, wchar_t* argv[]) {
#define PARAM_COUNT 2
HRESULT hr;
IDBCreateCommand * pIDBCreateCommand = NULL;
ICommandText * pICommandText = NULL;
ICommandPrepare * pICommandPrepare = NULL;
IAccessor * pIAccessor = NULL;
IRowset * pIRowset = NULL;
ICommandProperties * pICommandProperties = NULL;
HACCESSOR hAccessor;
DBBINDING dbBind[PARAM_COUNT];
DBROWCOUNT rows;
DBPROPSET rgCmdPropSet[1];
DBPROP rgCmdProperties[1];
if ( argc < 2 ) {
wprintf( L"Usage: %s: <server>\n", argv[0] );
return;
}
CoInitialize(NULL);
// Open connection to SS database.
hr = OpenSessionSS( &pIDBCreateCommand, argv[1] );
CHECK_HR_ERR(hr,MainCleanup);
// Get ICommandText.
hr = pIDBCreateCommand->CreateCommand( NULL, IID_ICommandText, (IUnknown**)&pICommandText );
printf( "pIDBCreateCommand->CreateCommand(...) returned 0x%08x.\n", hr );
CHECK_HR(hr,MainCleanup);
// Prepare the parameterized execute statement.
hr = pICommandText->SetCommandText( DBGUID_DBSQL, L"SELECT uid, val FROM [DBFsa]..[FSTRTable]" );
// Set up parameter value binding.
ZeroMemory( &dbBind, sizeof(dbBind) );
struct _DATA_BLOCK {
long f1;
long f1_status;
long f1_length;
unsigned long imageData_length;
long imageData_status;
IUnknown* imageData;
} DATA_BLOCK;
dbBind[0].iOrdinal= 1;
dbBind[0].dwPart= DBPART_VALUE | DBPART_STATUS | DBPART_LENGTH;
dbBind[0].eParamIO= DBPARAMIO_NOTPARAM;
dbBind[0].obValue= offsetof( _DATA_BLOCK, f1 );
dbBind[0].obStatus= offsetof( _DATA_BLOCK, f1_status );
dbBind[0].obLength= offsetof( _DATA_BLOCK, f1_length );
dbBind[0].wType= DBTYPE_I4;
dbBind[0].cbMaxLen= sizeof(int);
dbBind[1].iOrdinal= 2;
dbBind[1].dwPart= DBPART_VALUE | DBPART_STATUS;
dbBind[1].eParamIO= DBPARAMIO_NOTPARAM;
dbBind[1].obValue= offsetof( _DATA_BLOCK, imageData );
dbBind[1].obStatus= offsetof( _DATA_BLOCK, imageData_status );
dbBind[1].obLength = offsetof( _DATA_BLOCK, imageData_length );
dbBind[1].dwMemOwner = DBMEMOWNER_CLIENTOWNED;
dbBind[1].wType= DBTYPE_IUNKNOWN;
dbBind[1].pObject= new DBOBJECT;
dbBind[1].pObject->dwFlags = STGM_READ;
dbBind[1].pObject->iid = IID_ISequentialStream;
dbBind[1].cbMaxLen= 0;
hr = pICommandText->QueryInterface(IID_ICommandProperties, (void**) &pICommandProperties);
CHECK_HR_ERR( hr, MainCleanup );
rgCmdProperties[0].dwPropertyID = DBPROP_ACCESSORDER;
rgCmdProperties[0].vValue.vt = VT_I4;
rgCmdProperties[0].vValue.lVal = DBPROPVAL_AO_SEQUENTIAL;
rgCmdProperties[0].dwOptions = DBPROPOPTIONS_REQUIRED;
rgCmdProperties[0].colid = DB_NULLID;
rgCmdPropSet[0].guidPropertySet = DBPROPSET_ROWSET;
rgCmdPropSet[0].cProperties = 1;
rgCmdPropSet[0].rgProperties = rgCmdProperties;
hr = pICommandProperties->SetProperties(1, rgCmdPropSet);
CHECK_HR_ERR( hr, MainCleanup );
// Get an accessor for our binding.
hr = pICommandText->Execute( NULL, IID_IRowset, NULL, &rows, (IUnknown**) &pIRowset );
CHECK_HR_ERR(hr, MainCleanup);
printf( "pICommandText->Execute(...) returned 0x%08x.\n", hr );
hr = pIRowset->QueryInterface( IID_IAccessor, (void**)&pIAccessor );
printf( "pIRowset->QueryInterface( IID_IAccessor) returned 0x%08x.\n", hr );
CHECK_HR_ERR(hr,MainCleanup);
hr = pIAccessor->CreateAccessor( DBACCESSOR_ROWDATA,
PARAM_COUNT,
&dbBind[0],
sizeof(DATA_BLOCK),
&hAccessor,
NULL );
printf( "pIAccessor->CreateAccessor(...) returned 0x%08x.\n", hr );
CHECK_HR_ERR(hr,MainCleanup);
// Set the parameter values and status/length.
DATA_BLOCK.f1 = 1;
DATA_BLOCK.f1_status = DBSTATUS_S_OK;
DATA_BLOCK.f1_length = sizeof(int);
DATA_BLOCK.imageData = NULL;
DATA_BLOCK.imageData_status = DBSTATUS_S_OK;
DATA_BLOCK.imageData_length = 0;
HROW hRow[1];
HROW* pRow = hRow;
DBCOUNTITEM count;
hr = pIRowset->GetNextRows( DB_NULL_HCHAPTER, 0, 1, &count, &pRow );
CHECK_HR_ERR(hr, MainCleanup);
hr = pIRowset->GetData( hRow[0], hAccessor, &DATA_BLOCK );
CHECK_HR_ERR(hr, MainCleanup);
// Read and process 5000 bytes at a time.
if( DATA_BLOCK.imageData_status == DBSTATUS_S_ISNULL ) {
// Process NULL data.
}
else if( DATA_BLOCK.imageData_status == DBSTATUS_S_OK ) {
ISequentialStream * pISequentialStream;
BYTE * rgBuffer = new BYTE[1024*1024*4];
ULONG cb;
ULONGLONG total = 0;
pISequentialStream = (ISequentialStream *) DATA_BLOCK.imageData;
do {
cb = sizeof( rgBuffer );
pISequentialStream->Read(rgBuffer, // Buffer to write the data
1024*1024*4, // Number of bytes to get
&cb); // Number of bytes written to buffer
if (cb > 0) { // Check to see if we got data
total += cb;
printf( "Received %d bytes of data, total = %08I64x\n", cb, total );
}
} while (cb >= sizeof(rgBuffer));
delete rgBuffer;
}
else {
printf( "%08X Problem retrieving varbinary(max)\n", DATA_BLOCK.imageData_status );
}
MainCleanup:
SAFE_RELEASE( pICommandProperties );
SAFE_RELEASE( pIRowset );
SAFE_RELEASE( pIDBCreateCommand );
SAFE_RELEASE( pICommandText );
SAFE_RELEASE( pICommandPrepare );
SAFE_RELEASE( pIAccessor );
printf_s( "Test complete.\n" );
}