Memilih Field Pada TDBgrid

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;