PostgreSQL Query Refactoring

I have a simple table called events It has a date, start time, end time and status I have multiple events for the same date, start and end. To know if someone can make an appointment, I have to check if for that date and start, end I have a line that the status is false (not occupied). The table definition with some example code: CREATE SEQUENCE events_id_seq; CREATE TABLE events( id int4 NOT NULL DEFAULT nextval('events_id_seq'::regclass), event_date date NULL, status bool NULL DEFAULT false, event_start time NULL, event_end time NULL ) ; INSERT INTO events(event_date,status,event_start,event_end) VALUES ('2016-10-10', TRUE, '08:00:00','08:30:00'), ('2016-10-10', TRUE, '08:00:00','08:30:00'), ('2016-10-10', FALSE, '08:00:00','08:30:00'), ('2016-10-10', TRUE, '08:00:00','08:30:00'), ('2016-10-10', TRUE, '08:30:00','09:00:00'), ('2016-10-10', FALSE, '08:30:00','09:00:00'), ('2016-10-10', FALSE, '08:30:00','09:00:00'), ('2016-10-10', FALSE, '08:30:00','09:00:00'); select distinct event_date, event_start, event_end, ( select count(*) from events e1 where e1.status = false and e1.event_date = e.event_date and e1.event_start = e.event_start and e1.event_end = e.event_end ) as free_slots from events e order by event_date, event_start; http://sqlfiddle.com/#!15/698b7 It works, but since I'm not a SQL expert, I am just seeking advice on other forms to solve this, just to learn a little more.