对于SQL中
TEXT、IMAGE、MEMO字段存取
可以采用下列
: BLOB字段
读取: TBlobSTream* TemplateStream;
char* TempPlatePtr;
TemplateStream=
TBlobStream((TBlobField*)WebQuery->FieldByName (\"SearchTem\"),bmReadWrite);
TemplatePtr=
char[TemplateStream->Size]; TemplateStream->Read(TemplatePtr, TemplateStream->Size);
BLOB字段
写入: TBlobSTream* TemplateStream;
char* TempPlatePtr;
TemplateStream=
TBlobStream((TBlobField*)WebQuery->FieldByName (\"SearchTem\"),bmReadWrite);
TemplatePtr=
char[TemplateStream->Size]; TemplateStream->Write(TemplatePtr, TemplateStream->Size);
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补充:
获得字段
大小用
datalength SQL Server端要作
点设置: By default, WRITETEXT is a nonlogged operation. This means that
text or image data is not logged when it is written
o the database.To use WRITETEXT in its default, nonlogged state,
//注意!!
the system administrator must use the sp_dboption system stored
procedure to
select o/bulkcopy,//
which allows nonlogged data to be inserted.
做了试验,直接写SQL语句好象不行.
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些注意事项和个例子 在写入时:
(1)如果使用
是TTable,则要将其ReadOnly属性先置为false,然后
Edit; (2)如果使用
是TQuery,则要将其RequestLive属性先置为true,然后Edit; 使得TTable(TQuery)是可写
. 下面是
个使用TQuery往content表(主键file_id)中插入条记录例子, script为
个BLOB字段: TBlobStream *pScriptStream;
//插入
条记录 strSQL1=\"insert
ocontent(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
Blob数据LockMemories(NewsScript);
NewsScript.GetEdition(NewsScript.m_ScriptHead.
EditionNum); NewsScript.m_pScript=(BYTE *)GlobalLock(NewsScript.m_hScript);
(NewsScript.m_pScript!=NULL) {
//再将刚插入
记录读出来,使该Query和该条记录关联 strSQL1=\"selectfile_id,scriptfromcontentwherefile_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=
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);
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