latest_event.sql

-- http://sqlfiddle.com/#!17/9ba87/5
CREATE TABLE order_event(
  id int,
  order_id text,
  event_name text,
  created timestamp default CURRENT_TIMESTAMP
 );
 
 INSERT INTO order_event(id, order_id, event_name) VALUES
 (1, 123, 'event A'),
 (2, 123, 'event B'),
 (3, 123, 'event C'),
 (5, 456, 'event A'),
 (6, 789, 'event A'),
 (7, 789, 'event B'),
 (8, 321, 'event A'),
 (9, 321, 'event B'),
 (11, 321, 'event C'),
 (12, 321, 'event D')