vc中怎么通过ADO(或ODBC）存取，修改MS SQL中的image类型列，请详细一些，最好能有例程，分不是问题。

[chjcwl]

[chjcwl]

大家都没做过吗？请指导一下，急用。

[chjcwl]

UP~~~~~~~~~~

[蓄丰]

可以先删除在添加，可以作为修改
ADO中有AppendChunk()函数
或者动态生成一个SQL语句

[hujun614]

ADO的话，只有用GetChunk(),AppendChunk()来操作大字段数据。

[swordflying]

// ADOBlobDlg.cpp : implementation file
//

#include "stdafx.h"
#include "ADOBlob.h"
#include "ADOBlobDlg.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

extern CADOBlobApp theApp;
/////////////////////////////////////////////////////////////////////////////
// CAboutDlg dialog used for App About

class CAboutDlg : public CDialog
{
public:
CAboutDlg();

// Dialog Data
//{{AFX_DATA(CAboutDlg)
enum { IDD = IDD_ABOUTBOX };
//}}AFX_DATA

// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CAboutDlg)
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
//}}AFX_VIRTUAL

// Implementation
protected:
//{{AFX_MSG(CAboutDlg)
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
};

CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)
{
//{{AFX_DATA_INIT(CAboutDlg)
//}}AFX_DATA_INIT
}

void CAboutDlg::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
//{{AFX_DATA_MAP(CAboutDlg)
//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)
//{{AFX_MSG_MAP(CAboutDlg)
// No message handlers
//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CADOBlobDlg dialog

CADOBlobDlg::CADOBlobDlg(CWnd* pParent /*=NULL*/)
: CDialog(CADOBlobDlg::IDD, pParent)
{
//{{AFX_DATA_INIT(CADOBlobDlg)
m_UserName = _T("");
m_Old = _T("");
//}}AFX_DATA_INIT
// Note that LoadIcon does not require a subsequent DestroyIcon in Win32
m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
m_bModify = FALSE;
m_hPhotoBitmap = NULL;
m_pBMPBuffer = NULL;
}

void CADOBlobDlg::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
//{{AFX_DATA_MAP(CADOBlobDlg)
DDX_Control(pDX, IDC_DELETEUSER, m_buttonDeleteUser);
DDX_Control(pDX, IDC_PREVIOUSUSER, m_buttonPreviousUser);
DDX_Control(pDX, IDC_NEXTUSER, m_buttonNextUser);
DDX_Control(pDX, IDC_OLD, m_editOld);
DDX_Control(pDX, IDC_USERNAME, m_editUserName);
DDX_Control(pDX, IDC_SELECTPHOTO, m_buttonSelectPhoto);
DDX_Control(pDX, IDC_SAVEINFO, m_buttonSaveInfo);
DDX_Text(pDX, IDC_USERNAME, m_UserName);
DDX_Text(pDX, IDC_OLD, m_Old);
//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CADOBlobDlg, CDialog)
//{{AFX_MSG_MAP(CADOBlobDlg)
ON_WM_SYSCOMMAND()
ON_WM_PAINT()
ON_WM_QUERYDRAGICON()
ON_BN_CLICKED(IDC_ADDUSER, OnAddUser)
ON_EN_CHANGE(IDC_USERNAME, OnChangeUsername)
ON_EN_CHANGE(IDC_OLD, OnChangeOld)
ON_BN_CLICKED(IDC_SAVEINFO, OnSaveinfo)
ON_BN_CLICKED(IDC_SELECTPHOTO, OnSelectphoto)
ON_BN_CLICKED(IDC_NEXTUSER, OnNextUser)
ON_BN_CLICKED(IDC_PREVIOUSUSER, OnPreviousUser)
ON_BN_CLICKED(IDC_DELETEUSER, OnDeleteUser)
//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CADOBlobDlg message handlers

BOOL CADOBlobDlg::OnInitDialog()
{
CDialog::OnInitDialog();

ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
ASSERT(IDM_ABOUTBOX < 0xF000);

CMenu* pSysMenu = GetSystemMenu(FALSE);
if (pSysMenu != NULL)
{
CString strAboutMenu;
strAboutMenu.LoadString(IDS_ABOUTBOX);
if (!strAboutMenu.IsEmpty())
{
pSysMenu->AppendMenu(MF_SEPARATOR);
pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
}
}

SetIcon(m_hIcon, TRUE); // Set big icon
SetIcon(m_hIcon, FALSE); // Set small icon

m_bNewUser = FALSE;
m_pRecordset.CreateInstance("ADODB.Recordset");
HRESULT hr = m_pRecordset->Open("SELECT * FROM userphoto",_variant_t((IDispatch *)theApp.m_pConnection,true),adOpenDynamic,adLockPessimistic,adCmdText);
if(SUCCEEDED(hr))
{
ReadData();
}
ResetControls();
return TRUE; // return TRUE unless you set the focus to a control
}

/////////////////////读取记录集当前记录中数据，包括图像数据//////////////
void CADOBlobDlg::ReadData()
{
DestroyPhoto(); ///清除原图像
if(m_pRecordset->adoEOF||m_pRecordset->BOF)
{
m_UserName.Empty();
m_Old.Empty();
UpdateData(FALSE);
return;
}
long lDataSize = m_pRecordset->GetFields()->GetItem("photo")->ActualSize;
if(lDataSize > 0)
{
_variant_t varBLOB;
varBLOB = m_pRecordset->GetFields()->GetItem("photo")->GetChunk(lDataSize);
if(varBLOB.vt == (VT_ARRAY | VT_UI1))
{
if(m_pBMPBuffer = new char[lDataSize+1]) ///重新分配必要的存储空间
{
char *pBuf = NULL;
SafeArrayAccessData(varBLOB.parray,(void **)&pBuf);
memcpy(m_pBMPBuffer,pBuf,lDataSize); ///复制数据到缓冲区m_pBMPBuffer
SafeArrayUnaccessData (varBLOB.parray);
m_nFileLen = lDataSize;
m_hPhotoBitmap = BufferToHBITMAP(); ///生成BITMAP对象
}
}
}
m_UserName = m_pRecordset->GetCollect("username").bstrVal;
m_Old.Format("%d",m_pRecordset->GetCollect("old").lVal);
m_editUserName.EnableWindow();
m_editOld.EnableWindow();
m_buttonSelectPhoto.EnableWindow();
m_buttonDeleteUser.EnableWindow();
UpdateData(FALSE);
}

void CADOBlobDlg::OnSysCommand(UINT nID, LPARAM lParam)
{
if ((nID & 0xFFF0) == IDM_ABOUTBOX)
{
CAboutDlg dlgAbout;
dlgAbout.DoModal();
}
else
{
CDialog::OnSysCommand(nID, lParam);
}
}

/////////////////在屏幕上显示图像///////////////////
void CADOBlobDlg::DrawUserPhoto(int x, int y, CDC *pDC)
{
if(!m_hPhotoBitmap) return;
HBITMAP OldBitmap;
CDC MemDC;
MemDC.CreateCompatibleDC(pDC);
OldBitmap=(HBITMAP)MemDC.SelectObject(m_hPhotoBitmap);
pDC->BitBlt(x,y,100,130,&MemDC,0,0,SRCCOPY);
MemDC.SelectObject(OldBitmap);
}

void CADOBlobDlg::OnPaint()
{
CPaintDC dc(this);
if (IsIconic())
{
SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);

// Center icon in client rectangle
int cxIcon = GetSystemMetrics(SM_CXICON);
int cyIcon = GetSystemMetrics(SM_CYICON);
CRect rect;
GetClientRect(&rect);
int x = (rect.Width() - cxIcon + 1) / 2;
int y = (rect.Height() - cyIcon + 1) / 2;

// Draw the icon
dc.DrawIcon(x, y, m_hIcon);
}
else
{
DrawUserPhoto(50,30,&dc);
CDialog::OnPaint();
}
}

HCURSOR CADOBlobDlg::OnQueryDragIcon()
{
return (HCURSOR) m_hIcon;
}

void CADOBlobDlg::OnAddUser()
{
if(m_bModify)
{
int nRet = MessageBox("当前用户信息尚未保存，是否保存?","VC知识库 WWW.VCKBASE.COM",MB_YESNOCANCEL);
switch(nRet)
{
case IDCANCEL:
return;
case IDYES:
OnSaveinfo();
break;
case IDNO:
default:
break;
}
}
m_editUserName.EnableWindow();
m_editOld.EnableWindow();
m_buttonSelectPhoto.EnableWindow();
m_buttonDeleteUser.EnableWindow(FALSE);
m_Old = "";
m_UserName = "";
m_bModify = FALSE;
m_bNewUser = TRUE;
UpdateData(FALSE);
DestroyPhoto();
Invalidate();
}

//////////////删除用户//////////////
void CADOBlobDlg::OnDeleteUser()
{
m_pRecordset->Delete(adAffectCurrent);
if(m_pRecordset->adoEOF)
m_pRecordset->MoveLast();
ResetControls();
m_buttonDeleteUser.EnableWindow(FALSE);
ReadData();
Invalidate();
}

void CADOBlobDlg::OnChangeUsername()
{
m_bModify = TRUE;
m_buttonSaveInfo.EnableWindow();
}

void CADOBlobDlg::OnChangeOld()
{
m_bModify = TRUE;
m_buttonSaveInfo.EnableWindow();
}

////////////////保存用户信息/////////////////
void CADOBlobDlg::OnSaveinfo()
{
if(!m_bModify) return;
UpdateData();
if(m_pBMPBuffer == NULL || m_hPhotoBitmap == NULL || m_UserName == "" || m_Old == "")
{
AfxMessageBox("您没有提供完整的用户信息。\r\n这些信息包括:用户名、年龄、照片");
return;
}
m_buttonSaveInfo.EnableWindow(FALSE);
char *pBuf = m_pBMPBuffer;
VARIANT varBLOB;
SAFEARRAY *psa;
SAFEARRAYBOUND rgsabound[1];

if(m_bNewUser)
m_pRecordset->AddNew();
m_pRecordset->PutCollect("username",_variant_t(m_UserName));
m_pRecordset->PutCollect("old",atol(m_Old));
if(pBuf)
{
rgsabound[0].lLbound = 0;
rgsabound[0].cElements = m_nFileLen;
psa = SafeArrayCreate(VT_UI1, 1, rgsabound);
for (long i = 0; i < (long)m_nFileLen; i++)
SafeArrayPutElement (psa, &i, pBuf++);
varBLOB.vt = VT_ARRAY | VT_UI1;
varBLOB.parray = psa;
m_pRecordset->GetFields()->GetItem("photo")->AppendChunk(varBLOB);
}
m_pRecordset->Update();
m_buttonDeleteUser.EnableWindow();
ResetControls();
m_bNewUser = FALSE;
m_bModify = FALSE;
}

///////////选择BMP文件并加载到内存/////////////
void CADOBlobDlg::OnSelectphoto()
{
static char BASED_CODE szFilter[] = "BMP Files (*.bmp)|*.bmp|All Files (*.*)|*.*||";
CFileDialog dlg(TRUE,"BMP",NULL, OFN_HIDEREADONLY | OFN_OVERWRITEPROMPT,szFilter);
if(dlg.DoModal() == IDOK)
{
CString pathname = dlg.GetPathName();
DestroyPhoto();
LoadBMPFile(pathname);
m_hPhotoBitmap = BufferToHBITMAP();
m_bModify = TRUE;
m_buttonSaveInfo.EnableWindow();
Invalidate();
}
}

/////////////清除分配的对象/////////////
void CADOBlobDlg::DestroyPhoto()
{
if(m_hPhotoBitmap)
{
DeleteObject(m_hPhotoBitmap);
m_hPhotoBitmap = NULL;
}
if(m_pBMPBuffer)
{
delete m_pBMPBuffer;
m_pBMPBuffer = NULL;
}
}

/////////////加载BMP文件到内存//////////////
BOOL CADOBlobDlg::LoadBMPFile(const char *pBMPPathname)
{
CFile file;
if( !file.Open( pBMPPathname, CFile::modeRead) )
return FALSE;
m_nFileLen = file.GetLength();
m_pBMPBuffer = new char[m_nFileLen + 1];
if(!m_pBMPBuffer)
return FALSE;
if(file.ReadHuge(m_pBMPBuffer,m_nFileLen) != m_nFileLen)
return FALSE;
return TRUE;
}

///////////将内存中的BMP文件内容转换到HBITMAP///////
HBITMAP CADOBlobDlg::BufferToHBITMAP()
{
HBITMAP hBmp;
LPSTR hDIB,lpBuffer = m_pBMPBuffer;
LPVOID lpDIBBits;
BITMAPFILEHEADER bmfHeader;
DWORD bmfHeaderLen;

bmfHeaderLen = sizeof(bmfHeader);
strncpy((LPSTR)&bmfHeader,(LPSTR)lpBuffer,bmfHeaderLen);
if (bmfHeader.bfType != ((WORD) ('M' << 8) | 'B')) return NULL;
hDIB = lpBuffer + bmfHeaderLen;
BITMAPINFOHEADER &bmiHeader = *(LPBITMAPINFOHEADER)hDIB ;
BITMAPINFO &bmInfo = *(LPBITMAPINFO)hDIB ;
int nColors = bmiHeader.biClrUsed ? bmiHeader.biClrUsed : 1 << bmiHeader.biBitCount;
if( bmInfo.bmiHeader.biBitCount > 8 )
lpDIBBits = (LPVOID)((LPDWORD)(bmInfo.bmiColors + bmInfo.bmiHeader.biClrUsed) +
((bmInfo.bmiHeader.biCompression == BI_BITFIELDS) ? 3 : 0));
else
lpDIBBits = (LPVOID)(bmInfo.bmiColors + nColors);
CClientDC dc(this);
hBmp = CreateDIBitmap(dc.m_hDC,&bmiHeader,CBM_INIT,lpDIBBits,&bmInfo,DIB_RGB_COLORS);
return hBmp;
}


BOOL CADOBlobDlg::DestroyWindow()
{
DestroyPhoto();
return CDialog::DestroyWindow();
}

//////////////下一个用户信息///////////////
void CADOBlobDlg::OnNextUser()
{
if(m_bModify)///假如当前记录改动过，则保存
OnSaveinfo();
m_pRecordset->MoveNext();
if(m_pRecordset->adoEOF)
m_pRecordset->MoveLast();
ReadData();
ResetControls();
Invalidate();
}

/////////////上一个用户信息/////////////////
void CADOBlobDlg::OnPreviousUser()
{
if(m_bModify)///假如当前记录改动过，则保存
OnSaveinfo();
m_pRecordset->MovePrevious();
if(m_pRecordset->BOF)
m_pRecordset->MoveFirst();
ReadData();
ResetControls();
Invalidate();
}

////////////////判断是否是最后一个记录//////////////
BOOL CADOBlobDlg::LastRecord()
{
if(m_pRecordset->adoEOF)
{
m_editUserName.EnableWindow(FALSE);
m_editOld.EnableWindow(FALSE);
m_buttonSelectPhoto.EnableWindow(FALSE);
return TRUE;
}
m_pRecordset->MoveNext();
if(m_pRecordset->adoEOF)
{
m_pRecordset->MovePrevious();
return TRUE;
}
else
{
m_pRecordset->MovePrevious();
return FALSE;
}

}

////////////////判断是否是第一个记录////////////////
BOOL CADOBlobDlg::FirstRecord()
{
if(m_pRecordset->BOF)
{
m_editUserName.EnableWindow(FALSE);
m_editOld.EnableWindow(FALSE);
m_buttonSelectPhoto.EnableWindow(FALSE);
return TRUE;
}
m_pRecordset->MovePrevious();
if(m_pRecordset->BOF)
{
m_pRecordset->MoveFirst();
return TRUE;
}
else
{
m_pRecordset->MoveNext();
return FALSE;
}
}

void CADOBlobDlg::ResetControls()
{
BOOL IsFirstRecord = FirstRecord();
BOOL IsLastRecord = LastRecord();
m_buttonPreviousUser.EnableWindow(!IsFirstRecord);
m_buttonNextUser.EnableWindow(!IsLastRecord);
}