How to select all rows (records) in a DBGrid from code

procedure DBGridSelectAll(AGrid: TDBGrid) ;
begin
   AGrid.SelectedRows.Clear;
   with AGrid.DataSource.DataSet do
   begin
     DisableControls;
     First;
     try
       while not EOF do
       begin
         AGrid.SelectedRows.CurrentRowSelected := True;
         Next;
       end;
     finally
       EnableControls;
     end;
   end;
end;

//Usage:
//DBGridSelectAll(DBGrid1) ;