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Hello there,

I have the following construct, which works a little but not really
properly: I am using a MS Access Database, with the certain table
'EventTree'. 'EventTree' has 3 fields: 'ID' (Auto-Inc), 'Name' (Text),
and 'EventTree' (OLE). In my program I have a form, on which I have
placed a DBGrid (connected only to the 'Name'-field of the
'EventTree'-table) and a TTreeView-component.

What I want to do is to load TTreeView-data from the 'EventTree'-field,
and display it in the TTreeView-component. Of couse, I want to save
changes in the TTreeView-component to the table.

I started to implement this using a TBlobStream. In the procedure 'Load'
I have the following code:
   BlobStream:=TBlobStream.Create(TblEventTree.FieldByName(FnEventTree)
      as TBlobField,bmRead);
   if BlobStream<>nil then TvEventTree.LoadFromStream(BlobStream);
   BlobStream.Free;
In the corresponing procedure 'Save' you find the following code-pieces:

   with TblEventTree do
   begin
      Edit;
      BlobStream:=TBlobStream.Create(FieldByName(FnEventTree) as
TBlobField,bmReadWrite);
      TvEventTree.SaveToStream(BlobStream);
      Post;
   end;
   BlobStream.Free;

As I said, it works a little (loading the event-trees), but as soon as I
save it for the first time, the occur error-messages, when I scroll
through the dataset: 'BLOB already open' and 'BLOB not open'.

In the documentation and in most of the Delphi-literature you hardly
find anything about BlobStreams and how you can use they. If somebody of
you sees what I am doing wrong in my program, please send me corrections
or suggestions.

Thanx,
Mike

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