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영문

대형 데이터 설정(OLE DB)

이 예제에서는 BLOB 데이터를 설정하고 테이블을 만들어 예제 레코드를 추가한 다음 행 집합에서 해당 레코드를 인출하고 BLOB 필드의 값을 설정하는 방법을 보여 줍니다. 이 예제는 IA64에서 지원되지 않습니다.

자체의 저장소 개체에 대한 포인터를 전달하기 위해 소비자는 BLOB 열의 값을 바인딩하는 접근자를 만든 다음 IRowsetChange::SetData 또는 IRowsetChange::InsertRow 메서드를 호출합니다.

이 예제에는 Microsoft SQL Server 예제 및 커뮤니티 프로젝트(Microsoft SQL Server Samples and Community Projects) 홈 페이지에서 다운로드할 수 있는 AdventureWorks 예제 데이터베이스가 필요합니다.

보안 정보 보안 정보

가능하면 Windows 인증을 사용하십시오. Windows 인증을 사용할 수 없으면 런타임에 사용자에게 자격 증명을 입력하라는 메시지를 표시합니다. 자격 증명은 파일에 저장하지 않는 것이 좋습니다. 자격 증명을 유지하려면 Win32 crypto API를 사용하여 자격 증명을 암호화해야 합니다.

BLOB 데이터를 설정하려면

  1. BLOB 열에 액세스하는 방법을 설명하는 DBOBJECT 구조를 만듭니다. DBOBJECT 구조의 dwFlag 요소를 STGM_READ로 설정하고 iid 요소를 IID_ISequentialStream(표시할 인터페이스)으로 설정합니다.

  2. 행 집합 업데이트가 가능하도록 DBPROPSET_ROWSET 속성 그룹의 속성을 설정합니다.

  3. DBBINDING 구조의 배열을 사용하여 각 열에 대해 하나씩 바인딩 집합을 만듭니다. DBBINDING 구조의 wType 요소를 DBTYPE_IUNKNOWN으로 설정하고 pObject 요소를 앞에서 만든 DBOBJECT 구조를 가리키도록 설정합니다.

  4. 구조의 DBBINDINGS 배열에 있는 바인딩 정보를 사용하여 접근자를 만듭니다.

  5. GetNextRows 를 호출하여 다음 행을 행 집합으로 인출합니다. GetData 를 호출하여 행 집합에서 데이터를 읽습니다.

  6. 데이터를 설정하려면 데이터 및 길이 표시기가 포함된 저장소 개체를 만든 다음 해당 BLOB 열을 바인딩하는 접근자를 사용하여 IRowsetChange::SetData(또는 IRowsetChange::InsertRow)를 호출합니다.

설명

ole32.lib oleaut32.lib를 사용하여 컴파일하고 다음 C++ 코드 목록을 실행합니다. 이 응용 프로그램은 컴퓨터의 기본 SQL Server 인스턴스에 연결됩니다. 일부 Windows 운영 체제에서는 (localhost) 또는 (local)을 해당 SQL Server 인스턴스의 이름으로 변경해야 합니다. 명명된 인스턴스에 연결하려면 연결 문자열을 L"(local)"에서 L"(local)\\name"으로 변경합니다. 여기서 name은 명명된 인스턴스입니다. 기본적으로 SQL Server Express는 명명된 인스턴스에 설치됩니다. INCLUDE 환경 변수에 sqlncli.h가 들어 있는 디렉터리를 포함해야 합니다.

코드

// compile with: ole32.lib oleaut32.lib
#define UNICODE
#define DBINITCONSTANTS
#define INITGID
#define OLEDBVER 0x0250  // to include correct interfaces

#include <windows.h>
#include <stdio.h>
#include <stddef.h>
#include <iostream>
#include <oledb.h>
#include <oledberr.h>
#include <SQLNCLI.h>

using namespace std;

#define SAFE_RELEASE(pIUnknown) if(pIUnknown) (pIUnknown)->Release();
HRESULT GetCommandObject(REFIID riid, IUnknown** ppIUnknown);
HRESULT CreateTable(ICommandText* pICommandText);

class CSeqStream : public ISequentialStream {
public:
   // Constructors
   CSeqStream();
   virtual ~CSeqStream();

   virtual BOOL Seek(ULONG iPos);
   virtual BOOL Clear();
   virtual BOOL CompareData(void* pBuffer);
   virtual ULONG Length() { return m_cBufSize; };

   virtual operator void* const() { return m_pBuffer; };

   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);

private:
   ULONG m_cRef;   // reference count
   void* m_pBuffer;   // buffer
   ULONG m_cBufSize;   // buffer size
   ULONG m_iPos;   // current index position in the buffer
};

// class implementation
CSeqStream::CSeqStream() {
   m_iPos = 0;
   m_cRef = 0;
   m_pBuffer = NULL;
   m_cBufSize = 0;

   // The constructor AddRef's
   AddRef();
}

CSeqStream::~CSeqStream() {
   // Shouldn't have any references left ASSERT(m_cRef == 0);
   CoTaskMemFree(m_pBuffer);
}

ULONG CSeqStream::AddRef() {
   return ++m_cRef;
}

ULONG CSeqStream::Release() {
   // ASSERT(m_cRef);
   if (--m_cRef)
      return m_cRef;

   delete this;
   return 0;
}

HRESULT CSeqStream::QueryInterface(REFIID riid, void** ppv) {
   // ASSERT(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;
}

BOOL CSeqStream::Seek(ULONG iPos) {
   // Make sure the desired position is within the buffer
   // ASSERT(iPos == 0 || iPos < m_cBufSize);

   // Reset the current buffer position
   m_iPos = iPos;
   return TRUE;
}

BOOL CSeqStream::Clear() {
   // Frees the buffer
   m_iPos = 0;
   m_cBufSize = 0;

   CoTaskMemFree(m_pBuffer);
   m_pBuffer = NULL;

   return TRUE;
}

BOOL CSeqStream::CompareData(void* pBuffer) {
   // ASSERT(pBuffer);

   // Quick and easy way to compare user buffer with the stream
   return memcmp(pBuffer, m_pBuffer, m_cBufSize) == 0;
}

HRESULT CSeqStream::Read(void *pv, ULONG cb, ULONG* pcbRead) {
   // Parameter checking
   if (pcbRead)
      *pcbRead = 0;

   if (!pv)
      return STG_E_INVALIDPOINTER;

   if (cb == 0)
      return S_OK;

   // Actual code
   ULONG cBytesLeft = m_cBufSize - m_iPos;
   ULONG cBytesRead = cb > cBytesLeft ? cBytesLeft : cb;

   // if no more bytes to retrieve return 
   if (cBytesLeft == 0)
      return S_FALSE; 

   // Copy to users buffer the number of bytes requested or remaining
   memcpy(pv, (void*)((BYTE*)m_pBuffer + m_iPos), cBytesRead);
   m_iPos += cBytesRead;

   if (pcbRead)
      *pcbRead = cBytesRead;

   if (cb != cBytesRead)
      return S_FALSE; 

   return S_OK;
}

HRESULT CSeqStream::Write(const void *pv, ULONG cb, ULONG* pcbWritten) {
   // Parameter checking
   if (!pv)
      return STG_E_INVALIDPOINTER;

   if (pcbWritten)
      *pcbWritten = 0;

   if (cb == 0)
      return S_OK;

   // Enlarge the current buffer
   m_cBufSize += cb;

   // Need to append to the end of the stream
   m_pBuffer = CoTaskMemRealloc(m_pBuffer, m_cBufSize);
   memcpy((void*)((BYTE*)m_pBuffer + m_iPos), pv, cb);
   // m_iPos += cb;

   if (pcbWritten)
      *pcbWritten = cb;

   return S_OK;
}

int main() {
   CoInitialize(NULL);

   DBOBJECT ObjectStruct;
   ObjectStruct.dwFlags = STGM_READ;
   ObjectStruct.iid = IID_ISequentialStream;

   struct BLOBDATA {
      DBSTATUS dwStatus;   
      DBLENGTH dwLength; 
      ISequentialStream* pISeqStream;
   };

   BLOBDATA BLOBGetData;
   BLOBDATA BLOBSetData;

   const ULONG cBindings = 1;
   DBBINDING rgBindings[cBindings]; 
   HRESULT hr = S_OK;

   IAccessor* pIAccessor = NULL;
   ICommandText* pICommandText = NULL;
   ICommandProperties* pICommandProperties = NULL;
   IRowsetChange* pIRowsetChange = NULL;
   IRowset* pIRowset = NULL;
   CSeqStream* pMySeqStream = NULL;

   DBCOUNTITEM cRowsObtained = 0;
   HACCESSOR hAccessor = DB_NULL_HACCESSOR;
   DBBINDSTATUS rgBindStatus[cBindings];
   HROW* rghRows = NULL;

   const ULONG cPropSets = 1;
   DBPROPSET rgPropSets[cPropSets];
   const ULONG cProperties = 1;
   DBPROP rgProperties[cProperties];
   const ULONG cBytes = 10;

   BYTE pBuffer[cBytes];
   ULONG cBytesRead = 0;

   BYTE pReadData[cBytes];   // read BLOB data in this array
   memset(pReadData, 0xAA, cBytes);

   BYTE pWriteData[cBytes];   // write BLOB data from this array
   memset(pWriteData, 'D', cBytes);

   // Get Command object
   hr = GetCommandObject(IID_ICommandText, (IUnknown**)&pICommandText);
   if (FAILED(hr)) {
      printf("Failed to get ICommandText interface.\n");
      // Release any references and return.
      goto Exit;
   }

   // Create table with image column and index
   hr = CreateTable(pICommandText);
   if (FAILED(hr)) {
      printf("Failed to create table.\n");
      // Release any references and return.
      goto Exit;
   }

   // Set the DBPROPSET structure.  It is used to pass an array 
   // of DBPROP structures to SetProperties().
   rgPropSets[0].guidPropertySet = DBPROPSET_ROWSET;
   rgPropSets[0].cProperties = cProperties;
   rgPropSets[0].rgProperties = rgProperties;

   // Now set properties in the property group (DBPROPSET_ROWSET)
   rgPropSets[0].rgProperties[0].dwPropertyID = DBPROP_UPDATABILITY;
   rgPropSets[0].rgProperties[0].dwOptions = DBPROPOPTIONS_REQUIRED;
   rgPropSets[0].rgProperties[0].dwStatus = DBPROPSTATUS_OK;
   rgPropSets[0].rgProperties[0].colid = DB_NULLID;
   rgPropSets[0].rgProperties[0].vValue.vt = VT_I4;
   V_I4(&rgPropSets[0].rgProperties[0].vValue) = DBPROPVAL_UP_CHANGE;

   // Set the rowset properties
   hr = pICommandText->QueryInterface(IID_ICommandProperties,
      (void **)&pICommandProperties);

   if (FAILED(hr)) {
      printf("Failed to get ICommandProperties to set rowset properties.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pICommandProperties->SetProperties(cPropSets, rgPropSets);

   if (FAILED(hr)) {
      printf("Execute failed to set rowset properties.\n");
      // Release any references and return.
      goto Exit;
   }

   // Execute a command (SELECT * FROM TestISeqStream)
   hr = pICommandText->SetCommandText(DBGUID_DBSQL, L"SELECT * FROM TestISeqStream");

   if (FAILED(hr)) {
      printf("Failed to set command text SELECT * FROM.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pICommandText->Execute(NULL, 
      IID_IRowsetChange, 
      NULL, 
      NULL,
      (IUnknown**)&pIRowsetChange);

   if (FAILED(hr)) {
      printf("Failed to execute the command SELECT * FROM.\n");
      // Release any references and return.
      goto Exit;
   }

   // Fill the DBBINDINGS array.
   rgBindings[0].iOrdinal = 2;   // ordinal position
   rgBindings[0].obValue = offsetof(BLOBDATA, pISeqStream);
   rgBindings[0].obLength = offsetof(BLOBDATA, dwLength);
   rgBindings[0].obStatus = offsetof(BLOBDATA, dwStatus);
   rgBindings[0].pTypeInfo = NULL;
   rgBindings[0].pObject = &ObjectStruct;
   rgBindings[0].pBindExt = NULL;
   rgBindings[0].dwPart =  DBPART_VALUE | DBPART_STATUS | DBPART_LENGTH;
   rgBindings[0].dwMemOwner = DBMEMOWNER_CLIENTOWNED;
   rgBindings[0].eParamIO = DBPARAMIO_NOTPARAM;
   rgBindings[0].cbMaxLen = 0; 
   rgBindings[0].dwFlags = 0;
   rgBindings[0].wType = DBTYPE_IUNKNOWN;
   rgBindings[0].bPrecision = 0;
   rgBindings[0].bScale = 0;

   // Create an accessor using the binding information.
   hr = pIRowsetChange->QueryInterface(IID_IAccessor, (void**)&pIAccessor);
   if (FAILED(hr)) {
      printf("Failed to get IAccessor interface.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pIAccessor->CreateAccessor(DBACCESSOR_ROWDATA,
      cBindings,
      rgBindings, 
      sizeof(BLOBDATA),
      &hAccessor,
      rgBindStatus);

   if (FAILED(hr)) {
      printf("Failed to create an accessor.\n");
      // Release any references and return.
      goto Exit;
   }

   // get the first row.
   hr = pIRowsetChange->QueryInterface(IID_IRowset, (void **)&pIRowset);
   if (FAILED(hr)) {
      printf("Failed to get IRowset interface.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pIRowset->GetNextRows(NULL, 0, 1, &cRowsObtained, &rghRows);
   hr = pIRowset->GetData(rghRows[0], hAccessor, &BLOBGetData);

   // Verify the retrieved data, only if data is not null.
   if (BLOBGetData.dwStatus == DBSTATUS_S_ISNULL) {
      // Process null data
      printf("Provider returned a null value.\n");
   } 
   else if(BLOBGetData.dwStatus == DBSTATUS_S_OK) {
      // Provider returned a nonNULL value
      BLOBGetData.pISeqStream->Read( pBuffer, cBytes, &cBytesRead);

      if (memcmp(pBuffer, pReadData, cBytes) != 0) {
         // cleanup 
      }

      SAFE_RELEASE(BLOBGetData.pISeqStream);
   }

   // Set up data for SetData.
   pMySeqStream = new CSeqStream();

   // Put data into ISequentialStream object for the provider to write.
   pMySeqStream->Write(pWriteData, cBytes, NULL);

   BLOBSetData.pISeqStream = (ISequentialStream*)pMySeqStream;
   BLOBSetData.dwStatus = DBSTATUS_S_OK;
   BLOBSetData.dwLength = pMySeqStream->Length();

   // Set the data.
   hr = pIRowsetChange->SetData(rghRows[0], hAccessor, &BLOBSetData);
   if (FAILED(hr))     {
      printf("Failed to set data.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pIAccessor->ReleaseAccessor(hAccessor, NULL);
   if (FAILED(hr)) {
      printf("Failed to release accessor.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pIRowset->ReleaseRows(cRowsObtained, rghRows, NULL, NULL, NULL);

   if (FAILED(hr)) {
      printf("Failed to release rows.\n");
      // Release any references and return.
      goto Exit;
   }

Exit:
   // Release all allocated memory and release interface pointers.
   CoUninitialize();
}

HRESULT GetCommandObject(REFIID riid, IUnknown** ppIUnknown) {
   HRESULT hr = S_OK;

   // Local interface pointers, until a connection is made.
   IDBInitialize* pIDBInitialize = NULL;
   IDBProperties*  pIDBProperties = NULL;
   IDBCreateSession* pIDBCreateSession = NULL;
   IDBCreateCommand* pIDBCreateCommand = NULL;

   const ULONG cPropSets = 1;
   DBPROPSET rgPropSets[cPropSets];

   const ULONG cProperties = 4;
   DBPROP rgProperties[cProperties];

   // Initialize property values needed to establish connection.
   for ( ULONG i = 0 ; i < 4 ; i++ )
      VariantInit(&rgProperties[i].vValue);

   // Server name.
   rgProperties[0].dwPropertyID = DBPROP_INIT_DATASOURCE;
   rgProperties[0].vValue.vt = VT_BSTR;

   rgProperties[0].vValue.bstrVal = SysAllocString(L"(local)");
   rgProperties[0].dwOptions = DBPROPOPTIONS_REQUIRED;
   rgProperties[0].colid = DB_NULLID;

   // Database.
   rgProperties[1].dwPropertyID = DBPROP_INIT_CATALOG;
   rgProperties[1].vValue.vt = VT_BSTR;
   rgProperties[1].vValue.bstrVal = SysAllocString(L"AdventureWorks");
   rgProperties[1].dwOptions = DBPROPOPTIONS_REQUIRED;
   rgProperties[1].colid = DB_NULLID;

   rgProperties[2].dwPropertyID = DBPROP_AUTH_INTEGRATED;
   rgProperties[2].vValue.vt = VT_BSTR;
   rgProperties[2].vValue.bstrVal = SysAllocString(L"SSPI");
   rgProperties[2].dwOptions = DBPROPOPTIONS_REQUIRED;
   rgProperties[2].colid = DB_NULLID;

   // Properties are now set.  Next, construct DBPROPSET structure (rgInitPropSet) used to pass an 
   // array of DBPROP structures (InitProperties) to the SetProperties method.
   rgPropSets[0].guidPropertySet = DBPROPSET_DBINIT;
   rgPropSets[0].cProperties = cProperties;
   rgPropSets[0].rgProperties = rgProperties;

   // Get the IDBInitialize interface.
   hr = CoCreateInstance(CLSID_SQLNCLI11, 
      NULL, 
      CLSCTX_INPROC_SERVER,
      IID_IDBInitialize, 
      (void**)&pIDBInitialize);

   if (FAILED(hr)) {
      printf("Failed to get IDBInitialize interface.\n");
      // Release any references and return.
      goto Exit;
   }

   // Set initialization properties.
   hr = pIDBInitialize->QueryInterface(IID_IDBProperties, (void **)&pIDBProperties);
   if (FAILED(hr)) {
      printf("Failed to get IDBProperties interface.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pIDBProperties->SetProperties(cPropSets, rgPropSets);
   if (FAILED(hr)) {
      printf("Failed to set properties for DBPROPSET_DBINIT.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pIDBInitialize->Initialize();
   if (FAILED(hr)) {
      printf("Failed to initialize.\n");
      // Release any references and return.
      goto Exit;
   }

   // Create a session object.
   hr = pIDBInitialize->QueryInterface( IID_IDBCreateSession,
                                        (void **)&pIDBCreateSession);

   if (FAILED(hr)) {
      printf("Failed to get pIDBCreateSession interface.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pIDBCreateSession->CreateSession( NULL, IID_IDBCreateCommand, (IUnknown**)&pIDBCreateCommand);

   if (FAILED(hr)) {
      printf("Failed to create session object.\n");
      // Release any references and return.
      goto Exit;
   }

   // Get CommandText object
   hr = pIDBCreateCommand->CreateCommand( NULL, riid, (IUnknown**)ppIUnknown);

   if (FAILED(hr)) {
      printf("Failed to create CommandText object.\n");
      // Release any references and return.
      goto Exit;
   }

   return hr;

Exit:
   // Free up all allocated memory and release interface pointers.
   return hr;
}

HRESULT CreateTable(ICommandText* pICommandText) {
   HRESULT hr = S_OK;

   // drop the table "TestISeqStream" if the table exists.
   hr = pICommandText->SetCommandText( DBGUID_DBSQL, L"if object_id('TestISeqStream') is not null drop table TestISeqStream");
   if (FAILED(hr)) {
      printf("Failed to set command text DROP TABLE.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pICommandText->Execute(NULL, IID_NULL, NULL, NULL, NULL);
   if (FAILED(hr)) {
      printf("Failed to drop the table.\n");
      // Release any references and return.
      goto Exit;
   }

   // Create a new table.
   hr = pICommandText->SetCommandText(DBGUID_DBSQL, 
      L"CREATE TABLE TestISeqStream (col1 int,col2 image)");

   if (FAILED(hr)) {
      printf("Failed to set command text CREATE TABLE.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pICommandText->Execute(NULL, IID_NULL, NULL, NULL, NULL);
   if (FAILED(hr)) {
      printf("Failed to create table.\n");
      // Release any references and return.
      goto Exit;
   }

   // Insert one row into table.
   hr = pICommandText->SetCommandText(DBGUID_DBSQL,
      L"INSERT INTO TestISeqStream(col1,col2) VALUES (1,0xAAAAAAAAAAAAAAAAA)");
   if (FAILED(hr)) {
      printf("Failed to set command text INSERT INTO.\n");
      // Release any references and return.
      goto Exit;
   }

   hr = pICommandText->Execute(NULL, IID_NULL, NULL, NULL, NULL);

   if (FAILED(hr)) {
      printf("Failed to insert record in the table.\n");
      // Release any references and return.
      goto Exit;
   }

Exit:
   // Release all allocated memory and release interface pointers.
   return hr;
}

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