| OB字段数据时可用如下的方法：
BOOL SetBLOBData(WCHAR *awcname,CString strFile)
{
DBOBJECT ObjectStruct;
ObjectStruct.dwFlags = STGM_READ;
ObjectStruct.iid = IID_ISequentialStream;
struct BLOBDATA
{
DBSTATUS dwStatus;
DWORD dwLength;
ISequentialStream* pISeqStream;
};
BLOBDATA BLOBGetData;
BLOBDATA BLOBSetData;
const ULONG cBindings = 1;
DBBINDING rgBindings[cBindings];
HRESULT hr = S_OK;
IAccessor* pIAccessor = NULL;
ICommandProperties* pICommandProperties = NULL;
IRowsetChange* pIRowsetChange = NULL;
IRowset* pIRowset = NULL;
CSeqStream* pMySeqStream = NULL;
ULONG 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];
rgPropSets[0].guidPropertySet = DBPROPSET_ROWSET;
rgPropSets[0].cProperties = cProperties;
rgPropSets[0].rgProperties = rgProperties;
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;
//设置Rowset属性
hr = g_pICommandText->QueryInterface(IID_ICommandProperties,
(void **)&pICommandProperties);
if (FAILED(hr))
{
TRACE0("Failed to get ICommandProperties to set rowset properties. ");
return FALSE;
}
hr = pICommandProperties->SetProperties(cPropSets, rgPropSets);
if (FAILED(hr))
{
TRACE0("Execute failed to set rowset properties. ");
return FALSE;
}
//执行命令
CString strSql;
strSql.Format("SELECT Stream FROM tMaterials WHERE MaterialID = %s ",gToQuote(awcname));
int nlen=strSql.GetLength();
wchar_t *pSql=(wchar_t*)malloc(nlen*sizeof(wchar_t));
mbstowcs(pSql,strSql.GetBuffer(MAX_PATH),nlen);
if (FAILED(hr = g_pICommandText->SetCommandText(DBGUID_DBSQL,
pSql)))
{
TRACE0("failed");
return FALSE;
}
hr = g_pICommandText->Execute(NULL, IID_IRowsetChange, NULL, NULL,
(IUnknown**)&pIRowsetChange);
if (FAILED(hr))
{
TRACE0("Failed to execute the command ");
return FALSE;
}
rgBindings[0].iOrdinal = 1; //你的BLOB字段的位置（从1开始），改为你所需要的
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;
hr = pIRowsetChange->QueryInterface(IID_IAccessor,
(void**)&pIAccessor);
if (FAILED(hr))
{
TRACE0("Failed to get IAccessor interface. ");
return FALSE;
}
hr = pIAccessor->CreateAccessor(DBACCESSOR_ROWDATA,
cBindings,
rgBindings,
sizeof(BLOBDATA),
&hAccessor,
rgBindStatus);
if (FAILED(hr))
{
TRACE0("Failed to create an accessor. ");
return FALSE;
}
hr = pIRowsetChange->QueryInterface(IID_IRowset,
(void **)&pIRowset);
if (FAILED(hr))
{
TRACE0("Failed to get IRowset interface. ");
return FALSE;
}
hr = pIRowset->GetNextRows(NULL,0, 1,&cRowsObtained,&rghRows);
hr = pIRowset->GetData(rghRows[0],
hAccessor,
&BLOBGetData);
if (BLOBGetData.dwStatus == DBSTATUS_S_ISNULL)
//在数据库的当前字段为NULL
TRACE0("Provider returned a null value. ");
else if(BLOBGetData.dwStatus == DBSTATUS_S_OK)
{
//在这里，从服务端为你分配的ISequentialStream接口读入BLOB数据
//BLOBGetData.pISeqStream->Read(pBuffer,cBytes,&cBytesRead);
//无论你是否有读数据，
SAFE_RELEASE(BLOBGetData.pISeqStream);
}
//生成一个新的Stream.
pMySeqStream = new CSeqStream();
//开始从文件中读数据写入数据库
CFile fle;
if (fle.Open(strFile,CFile::modeRead))
{
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