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Database large object   Найти похожие ветки 

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Jon ©   (2007-09-24 02:49) [0]

With KOLEdb to get FieldByNameAsHex how can I find the size of the returned data in bytes? (I have image stored or binary data)

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thaddy   (2007-09-24 03:05) [1]

Use a memorystream and use memorystream.size ;-)

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Jon ©   (2007-09-24 12:14) [2]

That is what I though but I cannot get the data into the stream.
This is the code that I am trying:

var
 Stream: PStream;
 Blob: Pointer;
 QR: PQuery;
begin
 ...
 Stream := NewMemoryStream;
 try
   Blob := QR.FieldByNameAsHex["picblob"];  // Stream.Write requires var parameter
   Stream.Write(Blob,????);   // Write(var Buffer; Count: DWord)
   Stream.SaveToFile("c:\blob.bin",0,Stream.Size);
 finally
   Stream.Free;
 end;
end;

I think that I am not understanding the technique correctly.
Is there a working example to help me please? Thank you.

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Vladimir Kladov ©   (2007-09-24 18:09) [3]

I did not implement blobs in KOLEDb. Certainly this may be possible but changing code (may be a lot). It seems that this is not necessary for new DB engines like MS SQL 2000 / XP: there are no more restrictions for varchar field maximum size as earlier.

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Jon ©   (2007-09-24 18:37) [4]

Thanks - I am glad that it is KOLEDb and not me.

I think that adding blob support would be very useful.

MySQL VARCHAR max length is 255 before MySQL 5.0.3, and 65535 in 5.0.3 and later versions.

I shall try to hack KOLEDb, unless another method is recommended.

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