code: def sql(self) -> Optional[str]:
      return self.db_info.get(self.PARAM_QUERY) or self.db_info.get(
          self.PARAM_TABLE
      )
  
imports: from contextlib import contextmanager
  from typing import TYPE_CHECKING, Any, Callable, Dict, Iterator, Optional
  from funcy import compact, log_durations
  from dvc.exceptions import DvcException
  from dvc.log import logger
  from .base import Dependency
label_desc: Use image node_id 2 for calling the DbDependency obj's underlying member method code with example usage: obj.sql() and returns: unknown