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procedure Tform.Select_All_Rows;
begin
  if query.Active then
  begin
    query.First;
    while not(query.Eof) do
    begin
      dbgrid.SelectedRows.CurrentRowSelected := TRUE;
      query.Next;
    end;
    Application.ProcessMessages;
  end;
end;					

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function GridSelectAll(Grid:TDBGrid):LongInt;
begin
  Result:=0;
  Grid.SelectedRows.Clear;
  with Grid.DataSource.DataSet do begin
    First;
    DisableControls;
    try
      while not EOF do begin
        Grid.SelectedRows.CurrentRowSelected:=True;
        Inc(Result);
        Next;
      end;
    finally
      EnableControls;
    end;
  end;
end;