procedure TMainForm.Button1Click(Sender: TObject);
begin
DataSetBroker1.DataSet.Edit;
DataSetBroker1.DataSet.FieldByName('zd4').AsString :=Memo1.Text;
DataSetBroker1.DataSet.ApplyUpdates;
if SaveDialog1.Execute then
begin
TBlobField(DataSetBroker1.DataSet.FieldByName('zd4')).SaveToFile(SaveDialog1.FileName);
end;
end;