Queries that Return Zero Rows Raise Exception

[cancan101]

e.g. if you run:

from sqlalchemy.engine import create_engine

engine = create_engine("shillelagh://")
connection = engine.connect()

query = """SELECT country, SUM(cnt)
FROM "https://docs.google.com/spreadsheets/d/1_rN3lm0R_bU3NemO0s9pbFkY5LQPcuy1pscv8ZXPtg8/edit#gid=0"
WHERE cnt > 10
GROUP BY country"""
for row in connection.execute(query):
    print(row)

you get:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/alex/.pyenv/versions/my-app/lib/python3.10/site-packages/sqlalchemy/engine/result.py", line 964, in __iter__
    return self._iter_impl()
  File "/Users/alex/.pyenv/versions/my-app/lib/python3.10/site-packages/sqlalchemy/engine/result.py", line 637, in _iter_impl
    return self._iterator_getter(self)
  File "/Users/alex/.pyenv/versions/my-app/lib/python3.10/site-packages/sqlalchemy/util/langhelpers.py", line 1180, in __get__
    obj.__dict__[self.__name__] = result = self.fget(obj)
  File "/Users/alex/.pyenv/versions/my-app/lib/python3.10/site-packages/sqlalchemy/engine/result.py", line 361, in _iterator_getter
    make_row = self._row_getter
  File "/Users/alex/.pyenv/versions/my-app/lib/python3.10/site-packages/sqlalchemy/util/langhelpers.py", line 1180, in __get__
    obj.__dict__[self.__name__] = result = self.fget(obj)
  File "/Users/alex/.pyenv/versions/my-app/lib/python3.10/site-packages/sqlalchemy/engine/result.py", line 320, in _row_getter
    keymap = metadata._keymap
  File "/Users/alex/.pyenv/versions/my-app/lib/python3.10/site-packages/sqlalchemy/engine/cursor.py", line 1208, in _keymap
    self._we_dont_return_rows()
  File "/Users/alex/.pyenv/versions/my-app/lib/python3.10/site-packages/sqlalchemy/engine/cursor.py", line 1189, in _we_dont_return_rows
    util.raise_(
  File "/Users/alex/.pyenv/versions/my-app/lib/python3.10/site-packages/sqlalchemy/util/compat.py", line 207, in raise_
    raise exception
sqlalchemy.exc.ResourceClosedError: This result object does not return rows. It has been closed automatically

[cancan101]

I think this issue is caused by None being returned for the description:

shillelagh/src/shillelagh/backends/apsw/db.py

Lines 261 to 270 in 7afaf13

	def _get_description(self) -> Description:
	"""
	Return the cursor description.
	We only return name and type, since that's what we get from APSW.
	"""
	try:
	description = self._cursor.getdescription()
	except apsw.ExecutionCompleteError:
	return None

which then causes this error in sqla:
https://github.com/sqlalchemy/sqlalchemy/blob/3f00555a984e17eaa55fe37235baf6f75500c5ba/lib/sqlalchemy/engine/cursor.py#L1198

rather, I think an empty list should be returned.

According to this, a set should always be returned for a select: sqlalchemy/sqlalchemy#5433 (comment)

[cancan101]

There is some more clarification in apsw on this: rogerbinns/apsw#160