{Для уменьшения ADODB_TLB: оставить uses Windows, ActiveX, ComObj;
добавить
type
TOleEnum = type LongWord;
}

unit NBlobZlib;

interface
uses Windows, KOL, ADODB_TLB, KolZlib;

function StreamZCompress(Dest, Source: PStream): DWord;
function StreamZDecompress(Dest, Source: PStream; Count: DWord): DWord;
function WriteFileToBlob(const aFileName: KolString): OleVariant;
function WriteBlobToFile(aField: Field; const aFileName: KolString): OleVariant;

type
TBlobByteData = array of Byte;

const
 STRM_ERROR = DWord (-1);

implementation

function WriteFileToBlob(const aFileName: KolString): OleVariant;
 var F, M: PStream; B: TBlobByteData;
begin
   F:= NewReadFileStream(aFileName);
   M:= NewMemoryStream;
   try
  StreamZCompress(M, F);
    SetLength(B, M.Size);
     Move(M.Memory^, B[0], M.Size);
     Result:= B;
 finally
     Finalize(B);
    F.Free;
     M.Free;
   end;
end;

function WriteBlobToFile(aField: Field; const aFileName: KolString): OleVariant;
var Buf: Pointer; M, F: PStream;
begin
 Result:= Null;
   F:= NewWriteFileStream(aFileName);
   M:= NewMemoryStream;
   try
    Result:= AField.Value;
    Buf:= VarArrayLock(Result);
     M.Write(buf^, aField.ActualSize);
     StreamZDecompress(F, M, 0);
  finally
     VarArrayUnlock(Result);
    F.Free;
     M.Free;
   end;
end;

function StreamZDecompress(Dest, Source: PStream; Count: DWord): DWord;
var Zipper: PStream;
 Size: DWord;
 begin
   try
    Source.Seek(0, spBegin);
     if Source.Read (Size, 4) <> 4 then Exit;
     if not NewZLibDStream (Zipper, Source, nil) then Exit;
     Result:= Stream2Stream(Dest, Zipper, Size);
   finally
     if Zipper <> nil then Zipper.Free;
   end;
end;

function StreamZCompress(Dest, Source: PStream): DWord;
var  Zipper: PStream; Size: DWord;
begin
  Size:=Source.Size;
 Source.Seek(0, spBegin);
   Dest.Write (Size, 4);
   try
     If not NewZLibCStream (Zipper, clMax, Dest, nil) then Exit;
     Result:= Stream2Stream(Zipper, Source, Size);
   finally
     if Zipper <> nil then Zipper.Free;
   end;
end;