ODBC处理Image字段

在VC中使用CDBVariant变量存放image字段。先在CRecordset中执行select语句选出image
字
段（此处report字段为image类型）。以下为部分代码：
//读取
        CDBVariant dbvt;
        myrec.GetFieldValue("report",dbvt,SQL_C_BINARY);
        char *f;
        f=(char*)GlobalLock(dbvt.m_pbinary->m_hData);
        //以下为读取文件
        FILE* p=fopen("re_temp2","wb");
        for(int i=0;i<(int)dbvt.m_pbinary->m_dwDataLength;i++)
                fwrite(&f[i],1,1,p);
        fclose(p);
        GlobalUnlock(dbvt.m_pbinary->m_hData);
        myrec.Close();
//保存
                FILE * p=fopen("re_temp","rb");
                HGLOBAL gm;
                gm=GlobalAlloc(GMEM_MOVEABLE,1024*1024);
                char *f;
                f=(char *)GlobalLock(gm);
                long i=0;
                do{
                        fread(&f[i],1,1,p);
                        i++;
                }while(!feof(p));
                fclose(p);
                GlobalUnlock(gm);

                CGenRecord myrec(mydb);
                //mydb为指向CDatabase的指针，定义一个数据库连接
                //CGenRecord重载CRecord类，指向含image字段的表
                myrec.m_strFilter="rName='"+m_rName;
                myrec.m_strFilter+="'";
                myrec.Open(CRecordset::dynamic,NULL,CRecordset::none);
                myrec.Edit();
                HGLOBAL t1=myrec.m_report.m_hData;
                myrec.m_report.m_dwDataLength=i;
                myrec.m_report.m_hData=gm;
                myrec.SetFieldDirty(NULL);
                myrec.Update();
                myrec.m_report.m_hData=t1;
                GlobalFree(gm);
                myrec.Close();
                myrec.m_strFilter="";