BCB实现BLOB字段的读写 对于SQL中的TEXT、IMAGE、MEMO字段的存取，可以采用下列程序： BLOB字段的读取： TBlobSTream* TemplateStream; char* TempPlatePtr; TemplateStream=new TBlobStream((TBlobField*)WebQuery->FieldByName ("SearchTem"),bmReadWrite); TemplatePtr= new char[TemplateStream->Size]; TemplateStream->Read(TemplatePtr, TemplateStream->Size); BLOB字段的写入： TBlobSTream* TemplateStream; char* TempPlatePtr; TemplateStream=new TBlobStream((TBlobField*)WebQuery->FieldByName ("SearchTem"),bmReadWrite); TemplatePtr= new char[TemplateStream->Size]; TemplateStream->Write(TemplatePtr, TemplateStream->Size); ________________________________________________________________ 补充: 获得字段的大小用函数datalength SQL Server端要作一点设置: By default, WRITETEXT is a nonlogged operation. This means that text or image data is not logged when it is written into the database. To use WRITETEXT in its default, nonlogged state, //注意!! the system administrator must use the sp_dboption system stored procedure to set select into/bulkcopy, // which allows nonlogged data to be inserted. 做了试验,直接写SQL语句好象不行. ____________________________________________________________________ 一些注意事项和一个例子 在写入时: (1)如果使用的是TTable,则要将其ReadOnly属性先置为false,然后调用Edit函数; (2)如果使用的是TQuery,则要将其RequestLive属性先置为true,然后调用Edit函数; 使得TTable(TQuery)是可写的. 下面是一个使用TQuery往content表(主键file_id)中插入一条记录的例子, script为一个BLOB字段: TBlobStream *pScriptStream; //插入一条记录 strSQL1="insert into content(file_id,script,key_image) values('"; strSQL1=strSQL1+m_szFileID+"',null,null)"; dmStoryEditor->qryExec->SQL->Clear(); dmStoryEditor->qryExec->SQL->Add(strSQL1); dmStoryEditor->qryExec->ExecSQL(); dmStoryEditor->qryExec->Close(); //整理要写入的Blob数据 LockMemories(NewsScript); NewsScript.GetEdition(NewsScript.m_ScriptHead.byteEditionNum); NewsScript.m_pScript=(BYTE *)GlobalLock(NewsScript.m_hScript); if(NewsScript.m_pScript!=NULL) { //再将刚插入的记录读出来,使该Query与该条记录关联 strSQL1="select file_id,script from content where file_id='"+ m_szFileID+"'"; //允许该Query写 dmStoryEditor->qryExec->RequestLive=true; dmStoryEditor->qryExec->SQL->Clear(); dmStoryEditor->qryExec->SQL->Add(strSQL1); dmStoryEditor->qryExec->Open(); dmStoryEditor->qryExec->First(); //将该Query置为可写 dmStoryEditor->qryExec->Edit(); pScriptStream=new TBlobStream((TBlobField*)dmStoryEditor-> qryExec->FieldByName("script"),bmReadWrite); pScriptStream->Write(NewsScript.m_pScript, NewsScript.m_lScriptRealSize); dmStoryEditor->qryExec->Post(); dmStoryEditor->qryExec->RequestLive=false; delete pScriptStream; } GlobalUnlock(NewsScript.m_hScript); UnLockMemories(NewsScript);