Get percentage of group by

WITH number_of_tickets AS (
  SELECT user_id, COUNT(user_id) AS number_of_tickets_per_user
  FROM tickets 
  GROUP BY user_id
),
total_tickets AS (
  SELECT SUM(number_of_tickets_per_user) total_tickets
  FROM number_of_tickets
)
SELECT 
  user_id,
  number_of_tickets_per_user, 
  ROUND(number_of_tickets_per_user / total_tickets,3) percent
FROM number_of_tickets, total_tickets;

I would suggest to use window functions:

 SELECT DISTINCT user_id,
        (count(*) over (partition by user_id) / count(*) over ()::numeric)
   FROM tickets
   ORDER BY user_id;

 user_id |        ?column?
---------+------------------------
       1 | 0.06666666666666666667
       2 | 0.06666666666666666667
       3 | 0.20000000000000000000
       4 | 0.66666666666666666667
(4 rows)

Tags:

Postgresql

Group By

Related