Show ids for all templates not used by any document.
SELECT template_id FROM Templates EXCEPT SELECT template_id FROM Documents
SELECT template_id FROM Templates EXCEPT SELECT template_id FROM Documents
[{'Template_ID': 0}, {'Template_ID': 9}, {'Template_ID': 15}, {'Template_ID': 16}, {'Template_ID': 18}, {'Template_ID': 19}, {'Template_ID': 23}, {'Template_ID': 24}]