Gereralise the MYSQL query for all user_id

Question

I have a mysql query

select sum(duration),app_name,app_id,user_id 
from timesheet 
where user_id=164 
group by app_id 
order by sum(duration) desc 
limit 5;

The result is

sum(duration), app_name,       app_id, user_id
'626919371',   'Idle.exe',     '0',    '164'
'38220511',    'LockApp.exe', '2204',  '164'
'36675000',    '',            '1',     '164'
'27713000',    'LockApp.exe', '8148',  '164'
'16698661',    'chrome.exe',  '8548',  '164'

However I want the top 5 app for every user_id instead of just 164. Can you pelase guide me as to how this can be achieved in a single query. Or do I need to fire it for every individual user

Answer 1

This should work:

SELECT * 
FROM (
    SELECT *, rank() over (PARTITION BY user_id ORDER BY duration desc) AS rank  
    FROM (
        SELECT user_id, app_id, sum(duration) AS duration 
        FROM timesheet
        GROUP BY user_id, app_id
    ) sub2
) sub 
WHERE rank < 6

If you want the query to always return 5 rows per user (even if there are some top applications with the same rank) replace rank() with row_number()