결과 집합에서 행 인출(OLE DB)
이 예제에서는 결과 집합에서 행을 인출하는 방법을 보여 줍니다. 이 예제는 IA64에서 지원되지 않습니다.
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.
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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. |
예
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
int InitializeAndEstablishConnection();
int ProcessResultSet();
#define UNICODE
#define _UNICODE
#define DBINITCONSTANTS
#define INITGUID
#define OLEDBVER 0x0250 // to include correct interfaces
#include <stdio.h>
#include <tchar.h>
#include <stddef.h>
#include <windows.h>
#include <iostream>
#include <oledb.h>
#include <sqlncli.h>
#include <msdadc.h> // for IDataConvert
#include <msdaguid.h> // for IDataConvert
using namespace std;
IDBInitialize* pIDBInitialize = NULL;
IDBProperties* pIDBProperties = NULL;
IDBCreateSession* pIDBCreateSession = NULL;
IDBCreateCommand* pIDBCreateCommand = NULL;
ICommandText* pICommandText = NULL;
IRowset* pIRowset = NULL;
IColumnsInfo* pIColumnsInfo = NULL;
DBCOLUMNINFO* pDBColumnInfo = NULL;
IAccessor* pIAccessor = NULL;
DBPROP InitProperties[4];
DBPROPSET rgInitPropSet[1];
ULONG i, j;
HRESULT hr;
DBROWCOUNT cNumRows = 0;
DBORDINAL lNumCols;
WCHAR* pStringsBuffer;
DBBINDING* pBindings;
DBLENGTH ConsumerBufColOffset = 0;
HACCESSOR hAccessor;
DBCOUNTITEM lNumRowsRetrieved;
HROW hRows[10];
HROW* pRows = &hRows[0];
int main() {
// The command to execute.
WCHAR* wCmdString = OLESTR("SELECT StandardCost, ListPrice FROM Production.Product WHERE ListPrice > 14.00");
// Call a function to initialize and establish connection.
if (InitializeAndEstablishConnection() == -1) {
// Handle error.
cout << "Failed to initialize and connect to the server.\n";
return -1;
}
// Create a session object.
if (FAILED(pIDBInitialize->QueryInterface( IID_IDBCreateSession,
(void**) &pIDBCreateSession))) {
cout << "Failed to obtain IDBCreateSession interface.\n";
// Handle error.
return -1;
}
if (FAILED(pIDBCreateSession->CreateSession( NULL,
IID_IDBCreateCommand,
(IUnknown**) &pIDBCreateCommand))) {
cout << "pIDBCreateSession->CreateSession failed.\n";
// Handle error.
return -1;
}
// Access the ICommandText interface.
if (FAILED(pIDBCreateCommand->CreateCommand( NULL,
IID_ICommandText,
(IUnknown**) &pICommandText))) {
cout << "Failed to access ICommand interface.\n";
// Handle error.
return -1;
}
// Use SetCommandText() to specify the command text.
if (FAILED(pICommandText->SetCommandText(DBGUID_DBSQL, wCmdString))) {
cout << "Failed to set command text.\n";
// Handle error.
return -1;
}
// Execute the command.
if (FAILED(hr = pICommandText->Execute( NULL,
IID_IRowset,
NULL,
&cNumRows,
(IUnknown **) &pIRowset))) {
cout << "Failed to execute command.\n";
// Handle error.
return -1;
}
// Process the result set.
ProcessResultSet();
pIRowset->Release();
// Free up memory.
pICommandText->Release();
pIDBCreateCommand->Release();
pIDBCreateSession->Release();
if (FAILED(pIDBInitialize->Uninitialize())) {
// Uninitialize is not required, but it fails if an interface
// has not been released. This can be used for debugging.
cout << "Problem uninitializing.\n";
}
pIDBInitialize->Release();
CoUninitialize();
};
int InitializeAndEstablishConnection() {
CoInitialize(NULL);
// Obtain access to the SQLNCLI provider.
hr = CoCreateInstance( CLSID_SQLNCLI11,
NULL,
CLSCTX_INPROC_SERVER,
IID_IDBInitialize,
(void **) &pIDBInitialize);
if (FAILED(hr)) {
printf("Failed to get IDBInitialize interface.\n");
// Handle errors here.
return -1;
}
// Initialize the property values needed to establish the connection.
for ( i = 0 ; i < 4 ; i++ )
VariantInit(&InitProperties[i].vValue);
// Server name.
InitProperties[0].dwPropertyID = DBPROP_INIT_DATASOURCE;
InitProperties[0].vValue.vt = VT_BSTR;
InitProperties[0].vValue.bstrVal= SysAllocString(L"(local)");
InitProperties[0].dwOptions = DBPROPOPTIONS_REQUIRED;
InitProperties[0].colid = DB_NULLID;
// Database.
InitProperties[1].dwPropertyID = DBPROP_INIT_CATALOG;
InitProperties[1].vValue.vt = VT_BSTR;
InitProperties[1].vValue.bstrVal = SysAllocString(L"AdventureWorks");
InitProperties[1].dwOptions = DBPROPOPTIONS_REQUIRED;
InitProperties[1].colid = DB_NULLID;
InitProperties[2].dwPropertyID = DBPROP_AUTH_INTEGRATED;
InitProperties[2].vValue.vt = VT_BSTR;
InitProperties[2].vValue.bstrVal = SysAllocString(L"SSPI");
InitProperties[2].dwOptions = DBPROPOPTIONS_REQUIRED;
InitProperties[2].colid = DB_NULLID;
// Properties are set, now construct the DBPROPSET structure (rgInitPropSet) used to pass
// an array of DBPROP structures (InitProperties) to the SetProperties method.
rgInitPropSet[0].guidPropertySet = DBPROPSET_DBINIT;
rgInitPropSet[0].cProperties = 4;
rgInitPropSet[0].rgProperties = InitProperties;
// Set initialization properties.
hr = pIDBInitialize->QueryInterface(IID_IDBProperties, (void **)&pIDBProperties);
if (FAILED(hr)) {
cout << "Failed to get IDBProperties interface.\n";
// Handle errors here.
return -1;
}
hr = pIDBProperties->SetProperties(1, rgInitPropSet);
if (FAILED(hr)) {
cout << "Failed to set initialization properties.\n";
// Handle errors here.
return -1;
}
pIDBProperties->Release();
// Now establish the connection to the data source.
if (FAILED(pIDBInitialize->Initialize())) {
cout << "Problem in establishing connection to the data"
"source.\n";
// Handle errors here.
return -1;
}
return 0;
}
// Retrieve and display data resulting from a query.
int ProcessResultSet() {
// Obtain access to the IColumnInfo interface, from the Rowset object.
hr = pIRowset->QueryInterface(IID_IColumnsInfo, (void **)&pIColumnsInfo);
if (FAILED(hr)) {
cout << "Failed to get IColumnsInfo interface.\n";
// Handle errors here.
return -1;
}
// Retrieve the column information.
pIColumnsInfo->GetColumnInfo(&lNumCols, &pDBColumnInfo, &pStringsBuffer);
// Free the column information interface.
pIColumnsInfo->Release();
// Create a DBBINDING array.
DBBINDING * p = (pBindings = new DBBINDING[lNumCols]);
if (!(p /* pBindings = new DBBINDING[lNumCols] */ ))
return -1;
// Using the ColumnInfo structure, fill out the pBindings array.
for ( j = 0 ; j < lNumCols ; j++ ) {
pBindings[j].iOrdinal = j+1;
pBindings[j].obValue = ConsumerBufColOffset;
pBindings[j].pTypeInfo = NULL;
pBindings[j].pObject = NULL;
pBindings[j].pBindExt = NULL;
pBindings[j].dwPart = DBPART_VALUE;
pBindings[j].dwMemOwner = DBMEMOWNER_CLIENTOWNED;
pBindings[j].eParamIO = DBPARAMIO_NOTPARAM;
pBindings[j].cbMaxLen = (pDBColumnInfo[j].wType == DBTYPE_WSTR) ? pDBColumnInfo[j].ulColumnSize * 2 : pDBColumnInfo[j].ulColumnSize;
pBindings[j].dwFlags = 0;
pBindings[j].wType = pDBColumnInfo[j].wType;
pBindings[j].bPrecision = pDBColumnInfo[j].bPrecision;
pBindings[j].bScale = pDBColumnInfo[j].bScale;
// Compute the next buffer offset.
ConsumerBufColOffset =
ConsumerBufColOffset + pBindings[j].cbMaxLen;
};
// Get the IAccessor interface.
hr = pIRowset->QueryInterface(IID_IAccessor, (void **) &pIAccessor);
if (FAILED(hr)) {
cout << "Failed to obtain IAccessor interface.\n";
// Handle errors here.
return -1;
}
// Create an accessor from the set of bindings (pBindings).
pIAccessor->CreateAccessor(DBACCESSOR_ROWDATA, lNumCols, pBindings, 0, &hAccessor, NULL);
// Print column names.
for ( j = 0 ; j < lNumCols ; j++ )
printf("%-40S", pDBColumnInfo[j].pwszName);
printf("\n"); // new line after the column names
// Get a set of 10 rows.
pIRowset->GetNextRows( NULL, 0, 10, &lNumRowsRetrieved, &pRows);
// Allocate space for the row buffer.
BYTE * pBuffer = new BYTE[ConsumerBufColOffset];
if (!(pBuffer /* = new BYTE[ConsumerBufColOffset] */ )) {
// Free up all allocated memory.
pIAccessor->ReleaseAccessor(hAccessor, NULL);
pIAccessor->Release();
delete [] pBindings;
return 0;
}
// Create an instance of the data conversion library to convert DBTYPE_CY to string for display
IDataConvert* pIDataConvert;
CoCreateInstance(CLSID_OLEDB_CONVERSIONLIBRARY,
NULL,
CLSCTX_INPROC_SERVER,
IID_IDataConvert,
(void**)&pIDataConvert);
// variables used in DataConvert
DBLENGTH cbDstLength;
DBSTATUS dbsStatus;
char strCurrency0[25];
char strCurrency1[25];
// Display the rows.
while ( lNumRowsRetrieved > 0 ) {
// For each row, print the column data.
for ( j = 0 ; j < lNumRowsRetrieved ; j++ ) {
// Clear the buffer.
memset(pBuffer, 0, ConsumerBufColOffset);
// Get the row data values.
pIRowset->GetData(hRows[j], hAccessor, pBuffer);
// Convert DBTYPE_CY values to string
pIDataConvert->DataConvert(DBTYPE_CY, // wSrcType
DBTYPE_STR, // wDstType
sizeof(LARGE_INTEGER), // cbSrcLength
&cbDstLength, // pcbDstLength
&pBuffer[pBindings[0].obValue], // pSrc
strCurrency0, // pDst
sizeof(strCurrency0), //cbDstMaxLength
DBSTATUS_S_OK, // dbsSrcStatus
&dbsStatus, // pdbsStatus
0, // bPrecision (used for DBTYPE_NUMERIC only)
0, // bScale (used for DBTYPE_NUMERIC only)
DBDATACONVERT_DEFAULT); // dwFlags
pIDataConvert->DataConvert(DBTYPE_CY, // wSrcType
DBTYPE_STR, // wDstType
sizeof(LARGE_INTEGER), // cbSrcLength
&cbDstLength, // pcbDstLength
&pBuffer[pBindings[1].obValue], // pSrc
strCurrency1, // pDst
sizeof(strCurrency1), // cbDstMaxLength
DBSTATUS_S_OK, // dbsSrcStatus
&dbsStatus, // pdbsStatus
0, // bPrecision (used for DBTYPE_NUMERIC only)
0, // bScale (used for DBTYPE_NUMERIC only)
DBDATACONVERT_DEFAULT); // dwFlags
// Print cost and price values.
printf("%-40s%s\n", strCurrency0, strCurrency1); //sparra
};
// Release the rows retrieved.
pIRowset->ReleaseRows(lNumRowsRetrieved, hRows, NULL, NULL, NULL);
// Get the next set of 10 rows.
pIRowset->GetNextRows(NULL, 0, 10, &lNumRowsRetrieved, &pRows);
}
// Free up all allocated memory.
delete [] pBuffer;
pIAccessor->ReleaseAccessor(hAccessor, NULL);
pIAccessor->Release();
delete [] pBindings;
return 0;
}