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...save a file to a TBlobStream and read it back?
Autor: Mike Shkolnik
Homepage: http://www.scalabium.com
[ Print tip ]  

Tip Rating (53):  
     


{
  If you develop a database related software, then a very popular task is to
  save some files (documents/images/reports/etc) in some BLOB field of table
  and use these saved data later.
  In this tip I want to show how this task could be solved.
}

// To save a file to BLOB:
procedure TForm1.Button1Click(Sender: TObject);
var
  
blob: TBlobStream;
begin
  
blob := yourDataset.CreateBlobStream(yourDataset.FieldByName('YOUR_BLOB'), bmWrite);
  try
    
blob.Seek(0, soFromBeginning);
    fs := TFileStream.Create('c:\your_name.doc', fmOpenRead or
      
fmShareDenyWrite);
    try
      
blob.CopyFrom(fs, fs.Size)
    finally
      
fs.Free
    end;
  finally
    
blob.Free
  end;
end;
  // To load from BLOB:

procedure TForm1.Button1Click(Sender: TObject);
var
  
blob: TBlobStream;
begin
  
blob := yourDataset.CreateBlobStream(yourDataset.FieldByName('YOUR_BLOB'), bmRead);
  try
    
blob.Seek(0, soFromBeginning);

    with TFileStream.Create('c:\your_name.doc', fmCreate) do
      try
        
CopyFrom(blob, blob.Size)
      finally
        
Free
      end;
  finally
    
blob.Free
  end;
end;

{
  Using this code you can work with any database engine (BDE/ADO/DAO/ODBC/etc)
  and any file format (document of MS Word, spreadsheet of MS Excel, bitmap or
  jpeg pictures, wav-files etc)
}

 

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