def _get_tables_without_column_copies(sql_spans):
  """Returns a list of table names with no corresponding column copies."""
  table_names_from_columns = _get_table_names_from_columns(sql_spans)
  orphaned_tables = []
  for span in sql_spans:
    if (span.table_name and span.table_name not in table_names_from_columns and
        span.table_name not in orphaned_tables):
      orphaned_tables.append(span.table_name)
  return orphaned_tables
Returns a list of table names with no corresponding column copies.
language/xsp/data_preprocessing/abstract_sql.py