I got table:
id | nick | clanid | kills | deaths | map
1 | xdd | 2 | 123 | 23 | 'map_1'
2 | xd | 1 | 23 | 32 | 'map_1'
this table continuing with similar records. I need to get only 1 result, it's should be clanid and coef(kills/deaths), of course i need the clan with higher coef. This table got many records with players which have different clanids, kills, deaths and map.
The complete result i need: it's clanid with higher coef at current map.I tried SQL like that:
SELECT `clanid`, SUM(kills)/SUM(deaths) as 'coef'
FROM `test_user_stats`
WHERE `map`='map_1'
But that returs only 1 record with last clanid and his coef.
What i have to do next?(i obviously need to use LIMIT 1 and ORDER BY coef, but i got problems even without going so far).
Related
I have a table where I store a player ID and how many points they have, at the moment the only index is the player ID.
Like this:
+----------+--------+
| playerID | points |
+----------+--------+
| 1 | 14 |
| 2 | 18 |
| 3 | 0 |
| 4 | 55 |
+----------+--------+
At the moment I have ~100k players
What I want is given a player ID, what rank they are in terms of points I've got this query so far, however execution times are high > 0.5 seconds depending on how few points the player has.
SELECT playerID, count(playerID)
FROM playerRanks
WHERE points >=
(SELECT points
FROM playerRanks
WHERE playerID = '3')
Which will return this
+----------+------+
| playerID | rank |
+----------+------+
| 3 | 2 |
+----------+------+
I've tried adding an index on the points, but whilst that helps in the explain, it doesn't help execution times. Is there a better way of optimizing this, or is indexing Points the best? Alternatively, should I change the query?
I use MySQL for my database and i do some processing on the database side to make it easier for my application.
The queries i do used to be very fast until recently my database has lots of data and the queries are very very very slow.
My application do mainly statistics and has lots of related database to fetch data.
Here is an example:
tbl_game
+-------------------------------------+
| id | winner | duration| endedAt |
|--------+--------+---------+---------|
| 1 | 1 | 1200 |timestamp|
| 2 | 0 | 1200 |timestamp|
| 3 | 1 | 1200 |timestamp|
| 4 | 1 | 1200 |timestamp|
+-------------------------------------+
winner is either 0 or 1 for the team who won the game
duration is the number of seconds a game took
tbl_game_player
+-------------------------------------------------+
| gameId | playerId | playerSlot | frags | deaths |
|--------+----------+------------+-------+--------|
| 1 | 100 | 1 | 24 | 50 |
| 1 | 150 | 2 | 32 | 52 |
| 1 | 101 | 3 | 26 | 62 |
| 1 | 109 | 4 | 48 | 13 |
| 1 | 123 | 5 | 24 | 52 |
| 1 | 135 | 6 | 30 | 30 |
| 1 | 166 | 7 | 28 | 48 |
| 1 | 178 | 8 | 52 | 96 |
| 1 | 190 | 9 | 12 | 75 |
| 1 | 106 | 10 | 68 | 25 |
+-------------------------------------------------+
The details are only for the first game with id 1
1 game has 10 player slots where slot 1-5 = team 0 and 6-10 = team 1
There are more details in my real table this is just to give an overview.
So i need to calculate the statistics of each player in all the games. I created a view to accomplish this and it works fine when i have little data.
Here is an example:
+--------------------------------------------------------------------------+
| gameId | playerId | frags | deaths | actions | team | percent | isWinner |
|--------+----------+-------+--------+---------+------+---------+----------|
actions = frags + deaths
percent = (actions / sum(actions of players in the same team)) * 100
team is calculated using playerSlot in 1,2,3,4,5 or 6,7,8,9,10
isWinner is calculated by the team and winner
This is just 1 algorithm and i have many others to perform. My database is 1 milion + records and the queries are very slow.
here is the query for the above:
SELECT
tgp.gameId,
tgp.playerId,
tgp.frags,
tgp.deaths,
tgp.frags + tgp.deaths AS actions,
IF(playerSlot in (1,2,3,4,5), 0, 1) AS team,
((SELECT actions) / tgpx.totalActions) * 100 AS percent,
IF((SELECT team) = tg.winner, 1, 0) AS isWinner
FROM tbl_game_player tgp
INNER JOIN tbl_game tg on tgp.gameId = tg.id
INNER JOIN (
SELECT
gameId,
SUM(frags) AS totalFrags,
SUM(deaths) AS totalDeaths,
SUM(frags) + SUM(deaths) as totalActions,
IF(playerSlot in (1,2,3,4,5), 0, 1) as team
FROM tbl_game_player
GROUP BY gameId, team
) tgpx on tgp.gameId = tgpx.gameId and team = tgpx.team
It's quite obvious that indexes don't help you here¹, because you want all data from the two tables. You even want the data from tbl_game_player twice, once aggregated, once not aggregated. So there are millions of records to read and join. Your query is fine, and I see no way to improve it really.
¹ Of course you should always have indexes on primary and foreign keys, so the DBMS can make use of them in joins. (E.g. there should be an index on tbl_game(tgp.gameId)).
So your options lie outside the query:
Hardware (obviously).
Add a computed column for the team to tbl_game_player, so at least you save its evaluation when querying.
Partitions. One partition per team, so the aggregates can be calcualted separately.
Pre-computed data: Add a table tbl_game_team holding the sums; fill it with triggers. Thus you don't have to compute the aggregates in your query.
Data warehouse table: Make a table holding the complete result. Fill it with triggers or at intervals.
Setting up indexes would speed up your queries. Queries can take a while to run if there is a lot of results, this is definitely a start though.
for large databases Mysql INDEX can be very helpful in speed problems, An index can be created in a table to find data more quickly & efficiently. so must create index , you can learn more about MYsql index here http://www.w3schools.com/sql/sql_create_index.asp
Thanks for taking a look at this question. I'm kind of lost and hope someone can help me. Below is a update query i would like to run.
This query now returns an error:
1054 - Unknown column 'spi.et_cross_rank' in 'where clause'
Some background:
from table: tmp_ranking_tbl
I would like to get the nth(spi.et_return_rank) record
for a group with value x (spi.et_cross_rank)
SET #rownum=0;
UPDATE STRToer_Poule_indeling spi
SET spi.team_id = (SELECT R.team_poule_id
FROM (SELECT #rownum:=#rownum+1 AS rownum, trt.team_poule_id
FROM tmp_ranking_tbl trt
WHERE trt.overal_rank = spi.et_cross_rank
ORDER BY trt.punten DESC, (trt.goals_voor - trt.goals_tegen) DESC, trt.goals_voor DESC) R
WHERE R.rownum = spi.et_return_rank)
WHERE spi.et_ronde = v_et_ronde
AND spi.poule_id IN (SELECT row_id FROM STRToer_Poules WHERE toernooi_onderdeel_id=v_onderdeel_id) ;
Data in tmp_ranking_tbl looks like:
team_poule_id | punten | goals_voor | goals_tegen | overal_rank
65 | 6 | 10 | 10 | 2
69 | 6 | 9 | 10 | 2
75 | 7 | 11 | 4 | 2
84 | 6 | 6 | 8 | 2
112 | 5 | 7 | 7 | 2
Thanks in advance for the help!
Update after question in comment about the goal, i'll try to keep it short. :-)
This query is used on a website to keep scores of a tournament. Sometimes you have an odd number of teams going to the next round. At that point I want to select the best number 3(spi.et_cross_rank) team across poules. This is setting saved in the STRToer_Poule_indeling with what rank per poule and the 1st, 2nd or nth team(spi.et_return_rank). The table tmp_ranking_tbl is filled with all rank 3 teams across the poules. When this if filled I would like the 1st or 2nd, depedining on the setting in STRToer_Poule_indeling, record to return.
Subset of structure the STRToer_Poule_indeling table
row_id | team_id | et_ronde | et_cross_rank | et_return_rank
1 | null | 1 | 3 | 1
Just check if you have a column named et_cross_rank on your table STRToer_Poule_indeling
The problem seems to be that SQL can't find that column on your table.
Hope it helps.
I have a bidding system in place. The user enters how much he wants to bid, which then sends a request via ajax to a PHP script, which then gets what rank that bid would place under the existing bids, and then displays it back to the bidder. This allows him to increase his bid to get the rank he wants.
For example
+-----------+------------+
| bidder_id | bid_amount |
+-----------+------------+
| 1 | 20 |
| 2 | 20 |
| 3 | 30 |
| 5 | 40 |
| 6 | 10 |
+-----------+------------+
The user bids 15$, the query gets the rank as 5th.
How would this query look like? Is is possible to insert a fake row with the new user's bid and then order everything?
Something simple like this should do it;
SELECT COUNT(*)+1 rank
FROM bids
WHERE bid_amount > 15
An SQLfiddle to test with.
I've got a table with these columns:
id | player1_name | player1_score | player2_name | player2_score | player3_name | player3_score | player4_name | player4_score | player5_name | player5_score
Given a single row, how do I get the highest playerX_score and the corresponding playerX_name?
I've tried using GREATEST(), but I can't get the playerX_name.
As an aside, I think your table would be better designed as id | name | score | position | teamid, where position goes from 1 to 5 and teamid serves to group everyone in the same team together. It would make this sort of query much easier (greatest-score-per-team with associated rows).
However, here's one way to do what you want with your current table:
SELECT GREATEST(player1_score,player2_score,player3_score,
player4_score,player5_score) as score,
CASE GREATEST(...) -- repeat the above
WHEN player1_score then player1_name
WHEN player2_score then player2_name
WHEN player3_score then player3_name
WHEN player4_score then player4_name
WHEN player5_score then player5_name
END as name
FROM mytable
I think your table structure isn't right for what you're trying to do. You want the database to know that there's some relationship between player1_name and player1_score, but that's not encoded in the table. A change that would make this much easier would be to give each player their own record, and use what you're currently calling id (which I assume is the ID for a particular game) to indicate which players go together.
It would look like this:
game_id | player_num | player_name | score
1 | 1 | Octern | 100
1 | 2 | Boris | 400
1 | 3 | Jarlsberg | 300
1 | 4 | Pete | 40000
...
Then, to find the high scorer for a given game (in this case, game #1), you'd say:
select player_name from scores
WHERE game_id = 1
ORDER BY score desc
LIMIT 1