To realize a ranking system on my gameserver, I store some information about each player in a MySQL database. I've got the following database tables.
Table players
with example data:
id | steamId | deaths
---+---------+-------
1 | asdja | 2
2 | kfjsl | 5
Table weapons
with example data:
playerId | weaponId | kills
---------+----------+------
1 | 5 | 8
1 | 9 | 7
2 | 3 | 3
2 | 6 | 10
2 | 7 | 2
You see that I do not store the kills for each player in the players
-table, because I could simply calculate it from the weapons
-table.
I'm not very familiar with SQL queries, but I finished creating the following one to select a simple data set with following fields:
kills,
deaths,
kill-death-rate (kdrate),
count (maximum number of players),
rank (current ranking position, sorted by kills)
The query:
SELECT
SUM(weapons.kills) AS `kills`,
`deaths`,
(SUM(kills) / IF(deaths, deaths, 1)) AS `kdrate`,
(SELECT COUNT(*) FROM `players`) AS `count`,
(
SELECT
COUNT(*)
FROM
(
SELECT
p.id AS id2,
SUM(w.kills) AS kills2,
p.deaths AS deaths2,
p.steamId AS steamId2
FROM
weapons AS w,
players AS p
WHERE
p.id = w.playerId
GROUP BY
p.id
) AS temp
WHERE
temp.kills2 >= (
SELECT
SUM(weapons.kills) AS `kills`
FROM
`players`,
`weapons`
WHERE
players.id = weapons.playerId AND
`id` = 1
GROUP BY
`id`
)
ORDER BY
temp.kills2 DESC,
temp.deaths2 ASC,
temp.steamId2 ASC
) AS `rank`
FROM
`players`
INNER JOIN
`weapons`
ON
players.id = weapons.playerId
WHERE
`id` = 1
GROUP BY
`id`
There are two problems:
1.) The query is horrible.
2.) Executing this query with the given example data results in "the same rank". I mean, both players get the same rank because I the amount of kills is the same on both players. But instead, player 1 should be on rank 1 because he has less deaths than player 2. I don't know how I can realize this.
Thanks in advance!
EDIT: @Manueru_mx gave me a basic idea of how to do it: I've got the following code based on his answer:
SELECT
id,
kills,
deaths,
kdrate,
COUNT(*) AS rank,
(SELECT COUNT(*) FROM players) AS `count`
FROM
(
SELECT
pys.id AS id,
SUM(wps.kills) AS kills,
pys.deaths AS deaths,
(SUM(wps.kills) / pys.deaths) as kdrate
FROM
players pys
INNER JOIN
weapons wps
ON
pys.id = wps.playerid
GROUP BY
pys.id
ORDER BY
2 DESC,
3,
4 ASC
) AS tmp
WHERE
id = 1
The only problem left is, that the rank
is 1 in both cases.
This is my "solution". This query is more simple but get the results you are looking
select
pys.steamID, SUM(wps.kills) as Kills,
SUM(pys.deaths) as Deaths,
(sum(wps.kills)/sum(pys.deaths)) as kdratio
--,COUNT(pys.steamID) as PlayersC
from players pys
inner join weapons wps on pys.id = wps.playerid
group by pys.steamID
order by 2 DESC, 3, 4 ASC
Add the rank.
SELECT
id,
kills,
deaths,
kdrate,
ranking_usr as rank,
(SELECT COUNT(*) FROM players) AS `count`
FROM
(
SELECT
@row := @row + 1 AS ranking_usr
pys.id AS id,
SUM(wps.kills) AS kills,
pys.deaths AS deaths,
(SUM(wps.kills) / pys.deaths) as kdrate
FROM
players pys
INNER JOIN
weapons wps
ON
pys.id = wps.playerid
GROUP BY
pys.id
ORDER BY
2 DESC,
3,
4 ASC
) AS tmp
WHERE
id = 1