兄弟们，帮帮忙！关于怎么样添加二进制到sql server中的问题！

[kataboy]

首先说一下我的表结构：
表名：mytable
表的字段：
mydate datetime
mytime datetime
mydata image

以下是我操作表的代码：
1。保存的：
　String sql;
char *p;
TMemoryStream *ms = new(TMemoryStream);
p=new BYTE[257];

ms->WriteBuffer(p,256);
ShowMessage(IntToStr(ms->Position));
sql="Insert into mytable values(:pdate,:ptime,:pdata)";

Dm->AQ_Cpp->Close();
Dm->AQ_Cpp->SQL->Clear();
Dm->AQ_Cpp->SQL->Text=sql;
Dm->AQ_Cpp->Parameters->ParamByName("pdate")->DataType=ftDate;
Dm->AQ_Cpp->Parameters->ParamByName("pdate")->Value=Date();
Dm->AQ_Cpp->Parameters->ParamByName("ptime")->DataType=ftTime;
Dm->AQ_Cpp->Parameters->ParamByName("ptime")->Value=Time();
Dm->AQ_Cpp->Parameters->ParamByName("pdata")->LoadFromStream(ms,ftBlob);
Dm->AQ_Cpp->ExecSQL();
delete p;
delete ms;

以下是读取的：
　Dm->AQ_Cpp->Close();
Dm->AQ_Cpp->SQL->Clear();
Dm->AQ_Cpp->SQL->Text="select * from mytable";
Dm->AQ_Cpp->Open();

TMemoryStream *ms = new(TMemoryStream);
TBlobField *pbf;
char *p;
p=new BYTE[257];
ms->Clear();
pbf=(TBlobField*)Dm->AQ_Cpp->Fields->FieldByName("mydata");
pbf->SaveToStream(ms);
ms->ReadBuffer(p,256);//在这里就出错了。错误信息是：Stream read error!
for (int i=0;i<256;i++)
{
ShowMessage(IntToStr((int)p[i]));
}
delete ms;
delete p;

请大家帮我看看，为什么在读取时出错了，谢谢大家！

[domustdo]

pbf->SaveToStream(ms);
ms->Position=0; //加上这句试试
ms->ReadBuffer(p,256);

[kataboy]

谢谢，楼上的，可以了，不过问题又出来了。
我将读取的函数改为以下：

Dm->AQ_Cpp->Close();
Dm->AQ_Cpp->SQL->Clear();
Dm->AQ_Cpp->SQL->Text="select * from mytable";
Dm->AQ_Cpp->Open();
Dm->AQ_Cpp->Next();
TMemoryStream *ms = new(TMemoryStream);
TBlobField *pbf;
char *p;
p=new BYTE[257];
ms->Clear();
pbf=(TBlobField*)Dm->AQ_Cpp->Fields->FieldByName("mydata");
pbf->SaveToStream(ms);
ms->Position=0;
ms->ReadBuffer(p,256);
ListBox1->Items->Clear();
for (int i=0;i<256;i++)
{
ListBox1->Items->Add(IntToStr((int)p[i]));
}
delete ms;
delete p;

保存的为：
String sql;
char *p;
TMemoryStream *ms = new(TMemoryStream);
p=new BYTE[257];
p[0]=99;
ms->WriteBuffer(p,256);
ShowMessage(IntToStr(ms->Position));
sql="Insert into mytable values(:pdate,:ptime,:pdata)";

Dm->AQ_Cpp->Close();
Dm->AQ_Cpp->SQL->Clear();
Dm->AQ_Cpp->SQL->Text=sql;
Dm->AQ_Cpp->Parameters->ParamByName("pdate")->DataType=ftDate;
Dm->AQ_Cpp->Parameters->ParamByName("pdate")->Value=Date();
Dm->AQ_Cpp->Parameters->ParamByName("ptime")->DataType=ftTime;
Dm->AQ_Cpp->Parameters->ParamByName("ptime")->Value=Time();
Dm->AQ_Cpp->Parameters->ParamByName("pdata")->LoadFromStream(ms,ftBlob);
Dm->AQ_Cpp->ExecSQL();
delete p;
delete ms;


为什么我取取的数据第一个的值不是99呢？？？？

[domustdo]

p=new BYTE[257];
p[0]=99;
99用一个字节表示？这应该不行的

[domustdo]

它会转化为ASCII字符c

[kataboy]

谢谢！