What is the code of each location and the number of documents in that location?
SELECT location_code ,  count(*) FROM Document_locations GROUP BY location_code
SELECT location_code ,  count(*) FROM Document_locations GROUP BY location_code
[{'Location_Code': 'b', 'count(*)': 3}, {'Location_Code': 'c', 'count(*)': 2}, {'Location_Code': 'e', 'count(*)': 4}, {'Location_Code': 'n', 'count(*)': 1}, {'Location_Code': 'x', 'count(*)': 5}]