Get highest highscore entries between given dates - sql

Question

There is a scores_score table which contains following columns:
id, player_name, value, created_at
I have to fetch N (100) best scores where:
player_name must be unique across results
only best score for given player_name should be returned
results have to be filtered by date range
Lets say I have following data:
id player_name value date
1 A 400 2016-09-10
2 B 200 2016-09-12
3 C 400 2016-09-15
4 C 500 2016-09-14
5 B 100 2016-09-20
6 A 6000 2015-01-01
7 B 1200 2016-09-29
And want to get best players with their scores between 2016-09-01 and 2016-09-20. I should get the:
id player_name value date
4 C 500 2016-09-14
1 A 400 2016-09-10
2 B 200 2016-09-12
This is my approach to solve it, but there is an issue in nested SELECT as it fetches the best score of the player overall not within date ranges.
SELECT b.*, a.*
FROM (SELECT player_name, max(value) AS max_value
FROM scores_score
GROUP BY player_name
ORDER BY max(value) DESC) a
INNER JOIN scores_score b ON a.player_name = b.player_name AND a.max_value = b.value
WHERE CAST(b.created_at AS DATE) >= %(date_border)s
ORDER BY b.value DESC
LIMIT 100

Answer 1

distinct on
select *
from (
select distinct on (player_name) *
from scores_score
where date between '2016-09-01' and '2016-09-20'
order by player_name, value desc
) s
order by value desc
limit 100

Answer 2

This is going to work and will provide you with expected output. Use row_number() window function to mark highest score for each player between dates (rn = 1) and then order the result set by value descending and finally limit the output to 100 highest.
select
id, player_name, value, created_at
from (
select
id, player_name, value, created_at,
row_number() over (partition by player_name order by value desc, id) as rn
from scores_score
where created_at between '2016-09-01' and '2016-09-20'
) ranks
where rn = 1
order by value desc
limit 100
Note that additional column id for sorting within row_number function is to resolve ties (even though it assigns only one value per row within partition) that would involve the same player having two rows with equal values that are within given date. This would get older record and if they differ with created_at date you would see a difference in the output :-)

Answer 3

This one is a little cumbersome but should work. First select just the players and values within your date range (a). Then select the max score by player (b). Then join the id and date (c):
SELECT c.id, c.player_name, c.value, c.date
FROM
scores_score c
INNER JOIN
(SELECT player_name, max(value)
FROM
(SELECT player_name, value
FROM scores_score
WHERE date BETWEEN '2016-09-01' AND '2016-09-20') a
GROUP BY player_name) b
ON c.player_name = b.player_name
AND c.value = b.value
ORDER BY value
LIMIT 100
Tested here: http://sqlfiddle.com/#!9/10db42/6