text: BEGIN;
  
  CREATE TABLE transactions (
    id SERIAL PRIMARY KEY,
    customer_id integer NOT NULL,
    amount integer NOT NULL,
    purchased_at timestamp without time zone NOT NULL
  );
   
   
  INSERT INTO "transactions" (customer_id, amount, purchased_at) VALUES
  (1, 55, '2017-03-01 09:00:00'),
  (1, 125, '2017-03-01 10:00:00'),
  (1, 32, '2017-03-02 13:00:00'),
  (1, 64, '2017-03-02 15:00:00'),
  (1, 128, '2017-03-03 10:00:00'),
  (2, 333, '2017-03-01 09:00:00'),
  (2, 334, '2017-03-01 09:01:00'),
  (2, 333, '2017-03-01 09:02:00'),
  (2, 11, '2017-03-03 20:00:00'),
  (2, 44, '2017-03-03 20:15:00');
  
  COMMIT;