void AddDefaultColumnsForFragment(InputFragment input)
{
if (input is TableFragment)
{
AddDefaultColumnsForTable(input as TableFragment);
}
else if (input is JoinFragment)
{
JoinFragment j = input as JoinFragment;
AddDefaultColumnsForFragment(j.Left);
AddDefaultColumnsForFragment(j.Right);
}
else
throw new NotImplementedException();
}