What are ids of the all distinct orders, sorted by placement date?
SELECT DISTINCT order_id FROM orders ORDER BY date_order_placed
SELECT DISTINCT order_id FROM orders ORDER BY date_order_placed
[{'order_id': 15}, {'order_id': 2}, {'order_id': 4}, {'order_id': 6}, {'order_id': 12}, {'order_id': 7}, {'order_id': 11}, {'order_id': 10}, {'order_id': 3}, {'order_id': 9}, {'order_id': 8}, {'order_id': 14}, {'order_id': 13}, {'order_id': 1}, {'order_id': 5}]