怎样用ClientDataSet存取Oracle的BLOB字段?请各位大侠救命!!!

lixrun 2004-02-03 10:46:14
我的程序是:
if(DataModule1->ClientDataSet1->Active)
DataModule1->ClientDataSet1->Close();

DataModule1->ClientDataSet1->CommandText="";

DataModule1->ClientDataSet1->CommandText="insert into iconslib(id,libname,iconname,icon) values(icon_seq.nextval,:varlibname,:variconname,EMPTY_BLOB())";

DataModule1->ClientDataSet1->Params->Items[0]->AsString =LName;
DataModule1->ClientDataSet1->Params->Items[1]->AsString =IName;
DataModule1->ClientDataSet1->Params->Items[2]->LoadFromStream(IconStream,ftBlob);
DataModule1->ClientDataSet1->Execute();

if(DataModule1->ClientDataSet1->Active)
DataModule1->ClientDataSet1->Close();
DataModule1->ClientDataSet1->CommandText="";
DataModule1->ClientDataSet1->CommandText ="Select ICON from ICONSLIB where iconname=:iname for UPDATE";
//DataModule1->ClientDataSet1->Params->Items[0]->LoadFromStream(IconStream,ftBlob) ;
DataModule1->ClientDataSet1->Params->Items[0]->AsString=IName;
DataModule1->ClientDataSet1->Open();
TBlobStream *Stream=(TBlobStream *)DataModule1->ClientDataSet1->CreateBlobStream(DataModule1->ClientDataSet1->FieldByName("ICON"),bmRead);

if(MyCAD1->GetShapesCount())
MyCAD1->SaveToStream(Stream);
DataModule1->ClientDataSet1->Post();

DataModule1->ClientDataSet1->Close();

错误提示:数据类型不被支持
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GaoLun 2004-02-03
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BCB实现BLOB字段的读写
[ 作者:佚名 转贴自:未知 点击数:27 文章录入:foreknow ]
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);



lixrun 2004-02-03
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谢谢 GaoLun(★米老鼠★),问题我已经找到了,是ODBC DRIVERS的问题.

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