I have 2 tables:
Battles
--battleId(primary)--gameId(foreign)--endTime
BattleParticipants
--battleParticipantId(primary)--userId(foreign)--someNumerical--score--battleId(foreign)
Given userId, i want to get only ended battle data for each battle user participated in with additional player rank information and total number of player participated in battle information.Ended battle means battles only with endTime smaller than current_time
returned battle data should include:
battleId:
endTime:
gameId:
score:
someNumerical:
rankOfPlayerInBattle:
totalNumberOfPlayersParticipatedInBattle:
for each battle player participated.
With below query i can get battleId,endTime,gameId,score,someNumerical as i want:
SELECT b.battleId,b.endTime,b.gameId,bp.score,bp.someNumerical FROM battles b JOIN battleparticipants bp ON b.battleId=bp.battleId WHERE bp.userId="someuserid" AND b.endTime<CURRENT_TIMESTAMP
Given battleId and userId this query returns me rank of user in that battle:
SET #i=0;
SELECT battleId, userId,score, #i:=#i+1 AS myRank
FROM battleparticipants WHERE battleId="asd1234" AND userId="someuserid"
ORDER BY score DESC
Given battleId this query gives me total number of players participated in that battle:
SELECT COUNT(*) FROM battleparticipants WHERE battleId="asd1234"
So given those seperated queries how do i retrieve data i want in one query ? (i dont really need to use above queries i just gave them as example since they get datas i want seperately)
i cant add fiddle because for some reason create code is throwing error. for now i add pictures of tables and data:
Battles table:
BattleParticipants table:
Below query wrong result:
SELECT b.battleId,b.endTime,b.gameId,bp.score,bp.someNumerical , RANK()OVER(PARITITON BY b.battleId, bp.userId order by score desc) rankOfPlayerInBattle , BP_C.CNT totalNumberOfPlayersParticipatedInBattle
FROM battles b
JOIN battleparticipants bp ON b.battleId=bp.battleId
JOIN (SELECT battleId , COUNT(*) CNT FROM battleparticipants GROUP BY battleId) BP_C ON BP_C.battleId=bp.battleId
WHERE bp.userId="someuserid" AND b.endTime<CURRENT_TIMESTAMP
You can use above SQL.
Related
I have a table in which student marks in each subject and i have to get query in such a way that i will able to get all top 5 student in every subject who secure highest marks.
Here is a sample table:
My expected output look somthing like :
Top five student in PCM, ART, PCB on the basis of students marks,And also if two or more student secure same than those record also need to be in list with single query.
Original Answer
Technically, what you want to accomplish is not possible using a single SQL query. Had you only wanted one student per subject you could have achieved that using GROUP BY, but in your case it won't work.
The only way I can think of to get 5 students for each subject would be to write x queries, one for each subject and use UNION to glue them together. Such query will return a maximum of 5x rows.
Since you want to get the top 5 students based on the mark, you will have to use an ORDER BY clause, which, in combination with the UNION clauses will cause an error. To avoid that, you will have to use subqueries, so that UNION and ORDER BY clauses are not on the same level.
Query:
-- Select the 5 students with the highest mark in the `PCM` subject.
(
SELECT *
FROM student
WHERE subject = 'PCM'
ORDER BY studentMarks DESC
LIMIT 5
)
UNION
(
SELECT *
FROM student
WHERE subject = 'PCB'
ORDER BY studentMarks DESC
LIMIT 5
)
UNION
(
SELECT *
FROM student
WHERE subject = 'ART'
ORDER BY studentMarks DESC
LIMIT 5
);
Check out this SQLFiddle to evaluate the result yourself.
Updated Answer
This update aims to allow getting more than 5 students in the scenario that many students share the same grade in a particular subject.
Instead of using LIMIT 5 to get the top 5 rows, we use LIMIT 4,1 to get the fifth highest grade and use that to get all students that have a grade more or equal to that in a given subject. Though, if there are < 5 students in a subject LIMIT 4,1 will return NULL. In that case, we want essentially every student, so we use the minimum grade.
To achieve what is described above, you will need to use the following piece of code x times, as many as the subjects you have and join them together using UNION. As can be easily understood, this solution can be used for a small handful of different subjects or the query's extent will become unmaintainable.
Code:
-- Select the students with the top 5 highest marks in the `x` subject.
SELECT *
FROM student
WHERE studentMarks >= (
-- If there are less than 5 students in the subject return them all.
IFNULL (
(
-- Get the fifth highest grade.
SELECT studentMarks
FROM student
WHERE subject = 'x'
ORDER BY studentMarks DESC
LIMIT 4,1
), (
-- Get the lowest grade.
SELECT MIN(studentMarks)
FROM student
WHERE subject = 'x'
)
)
) AND subject = 'x';
Check out this SQLFiddle to evaluate the result yourself.
Alternative:
After some research I found an alternative, simpler query that will yield the same result as the one presented above based on the data you have provided without the need of "hardcoding" every subject in its own query.
In the following solution, we define a couple of variables that help us control the data:
one to cache the subject of the previous row and
one to save an incremental value that differentiates the rows having the same subject.
Query:
-- Select the students having the top 5 marks in each subject.
SELECT studentID, studentName, studentMarks, subject FROM
(
-- Use an incremented value to differentiate rows with the same subject.
SELECT *, (#n := if(#s = subject, #n +1, 1)) as n, #s:= subject
FROM student
CROSS JOIN (SELECT #n := 0, #s:= NULL) AS b
) AS a
WHERE n <= 5
ORDER BY subject, studentMarks DESC;
Check out this SQLFiddle to evaluate the result yourself.
Ideas were taken by the following threads:
Get top n records for each group of grouped results
How to SELECT the newest four items per category?
Select X items from every type
Getting the latest n records for each group
Below query produces almost what I desired, may this query helps others in future.
SELECT a.studentId, a.studentName, a.StudentMarks,a.subject FROM testquery AS a WHERE
(SELECT COUNT(*) FROM testquery AS b
WHERE b.subject = a.subject AND b.StudentMarks >= a.StudentMarks) <= 2
ORDER BY a.subject ASC, a.StudentMarks DESC
I have a relatively simple question but I'm stuck with writing a proper SQL query to display the results that I need. I have a table which stores results from matches with columns indicating the IDs of the players that took part in the match, the winner and another boolean column which let's say indicates whether I want to include that match in the result or not. So the columns are:
player1_id | player2_id | winner_id | use
So winner_id is the value from one of the first two columns depending on which player won. If I want to count how many times a certain player won a game just using the rows where the use flag is up, I can easily do so with:
SELECT COUNT(*) AS total, winner_id
FROM table
WHERE use = 1
GROUP BY winner_id
ORDER BY total DESC
However, I also want to do the same count but for the players that lost their matches. In other words, I want to group not by the winner_id but by the loser id, which would be the value of either player1_id or player2_id depending on which one of them is different from the winner_id. Any clues on how to do that with a simple query that works?
You can do like this to count the loosers:
SELECT
COUNT(*) AS total,
IF(player1_id = winner_id, player2_id, player1_id) AS looser_id
FROM table
WHERE use = 1
GROUP BY looser_id
ORDER BY total DESC
Is it possible to do a For or While loop in MYSQL?
I've got the following code extract, but the full code goes up to home_id_15, home_score_15, away_id_15 and away_score_15:
$query3 = '
SELECT match_date, fixture_id, COUNT(a.home) AS home, SUM(a.points) AS points FROM
(
SELECT match_date, fixture_id, home_id_1 AS home, home_score_1 AS points FROM scores
WHERE home_id_1 =' .intval($_REQUEST['ID']).'
UNION ALL
SELECT match_date, fixture_id, away_id_1 AS home, away_score_1 AS points
FROM scores
WHERE away_id_1 =' .intval($_REQUEST['ID']).'
UNION ALL
SELECT match_date, fixture_id, home_id_2 AS home, home_score_2 AS points
FROM scores
WHERE home_id_2 =' .intval($_REQUEST['ID']).'
UNION ALL
SELECT match_date, fixture_id, away_id_2 AS home, away_score_2 AS points
FROM scores
WHERE away_id_2 =' .intval($_REQUEST['ID']).'
UNION ALL) a
GROUP BY match_date'
The first and second sub-SELECTS are basically being repeated until they reach 15.
This seems a bit long-winded and I was wondering if it's possible to use a loop in MYSQL to output
home_id_1, home_score_1, away_id_1, away_score_1 [up to] home_id_15, home_score_15, away_id_15, away_score_15
, respectively?
Thanks,
Dan.
It looks like you might need to normalize your database a little bit more. Let's say you had 6 scores for each row. Instead of making each score a column, make a separate table called "scores" or something like that with a foreign key column and a score column. Then join the table with this scores table.
Example:
TABLE: team
team_id
name
TABLE: scores
team_id
score
SELECT t.*, s.score
FROM team t
join scores s
on t.team_id=s.team_id;
Todo: Add the concept of matches into your schema and the Join
I'm having trouble trying to sum a field GROUPED BY a common user ID from TWO DIFFERENT tables.
To give you a little more info... I am trying to track player performances by date (i.e.: most points scored on ALL Nov. 14's). The database is split, one table for regular season games and one table for playoffs. So, for example, a player may have played a regular season game on May 3, 2001....but a playoff game on May 3, 2005.
So, I'm trying to build a view with the sums of every player on all dates.
What I have for a single table:
SELECT PlayerId,sum(Points) as TOT_PTS
FROM RS_games
WHERE DAY(Date)=$cur_day
AND MONTH(Date)=$cur_month
GROUP BY PlayerId
...but I can't figure how I could sum the values of each player across two tables without creating a third view as a "stepping stone".
Any ideas?
If you want the results by (DAY-MONTH) you can do:
SELECT playerID,
CONCAT (DAY(DATE), '-', MONTH(DATE)) AS DAY_MONTH,
SUM(points) AS Total_Points
FROM (
SELECT playerID, DATE, points
FROM rs_games
UNION ALL
SELECT playerID, DATE, points
FROM po_games
) a
GROUP BY 1, 2
sqlfiddle demo
This way, you would end up with a result with every playerId,dd-mm, and the sum of points that were scored in that specific day across the years.
Just to lay out what I was saying:
select
ALL_players.PlayerID as PlayerID
COALESCE(reg.Points, 0) + COALESCE(po.Points, 0) as Points
from
ALL_players
left join
(select PlayerID, DATE(Date) as Date, sum(Points) as Points
from RS_games
WHERE DAY(Date)=$cur_day AND MONTH(Date)=$cur_month
group by PlayerID) as reg
on reg.PlayerID = ALL_players.PlayerID
left join
(select PlayerID, DATE(Date) as Date, sum(Points) as Points
from PO_games group by DATE(Date), PlayerID
WHERE DAY(Date)=$cur_day AND MONTH(Date)=$cur_month
group by PlayerID) as po
on po.PlayerID = ALL_players.PlayerID
EDIT: Looking again at requirements this will need either a full outer join or some adjustment... adjusting (should be working now)
I have a MySQL table where there are many rows for each person, and I want to write a query which aggregates rows with special constraint. (one per person)
For example, lets say the table is consist of following data.
name date reason
---------------------------------------
John 2013-04-01 14:00:00 Vacation
John 2013-03-31 18:00:00 Sick
Ted 2012-05-06 20:00:00 Sick
Ted 2012-02-20 01:00:00 Vacation
John 2011-12-21 00:00:00 Sick
Bob 2011-04-02 20:00:00 Sick
I want to see the distribution of 'reason' column. If I just write a query like below
select reason, count(*) as count from table group by reason
then I will be able to see number of reasons for this table overall.
reason count
------------------
Sick 4
Vacation 2
However, I am only interested in single reason from each person. The reason that should be counted should be from a row with latest date from the person's records. For example, John's latest reason would be Vacation while Ted's latest reason would be Sick. And Bob's latest reason (and the only reason) is Sick.
The expected result for that query should be like below. (Sum of count will be 3 because there are only 3 people)
reason count
-----------------
Sick 2
Vacation 1
Is it possible to write a query such that single latest reason will be counted when I want to see distribution(count) of reasons?
Here are some facts about the table.
The table has tens of millions of rows
For most of times, each person has one reason.
Some people have multiple reasons, but 99.99% of people have fewer than 5 reasons.
There are about 30 different reasons while there are millions of distinct names.
The table is partitioned based on date range.
SELECT T.REASON, COUNT(*)
FROM
(
SELECT PERSON, MAX(DATE) AS MAX_DATE
FROM TABLE-NAME
GROUP BY PERSON
) A, TABLE-NAME T
WHERE T.PERSON = A.PERSON AND T.DATE = A.MAX_DATE
GROUP BY T.REASON
Try this
select reason, count(*) from
(select reason from table where date in
(select max(date) from table group by name)) t
group by reason
In MySQL, it's not very efficient to do this kind of query since you don't have access to tools like partitionning query in SQL Server or Oracle.
You can still emulate it by doing a subquery and retrieve the rows based on the condition you need, here the maximum date :
SELECT t.reason, COUNT(1)
FROM
(
SELECT name, MAX(adate) AS maxDate
FROM #aTable
GROUP BY name
) maxDateRows
INNER JOIN #aTable t ON maxDateRows.name = t.name
AND maxDateRows.maxDate = t.adate
GROUP BY t.reason
You can see a sample here.
Test this query on your samples, but I'm afraid that it will be slow as hell.
For your information, you can do the same thing in a more elegant and much much faster way in SQL Server :
SELECT reason, COUNT(1)
FROM
(
SELECT name
, reason
, RANK() OVER(PARTITION BY name ORDER BY adate DESC) as Rank
FROM #aTable
) AS rankTable
WHERE Rank = 1
GROUP BY reason
The sample is here
If you are really stuck to MySql, and the first query is too slow, then you can split the problem.
Do a first query creating a table:
CREATE TABLE maxDateRows AS
SELECT name, MAX(adate) AS maxDate
FROM #aTable
GROUP BY name
Then create index on both name and maxDate.
Finally, get the results :
SELECT t.reason, COUNT(1)
FROM maxDateRows m
INNER JOIN #aTable t ON m.name = t.name
AND m.maxDate = t.adate
GROUP BY t.reason
The solution you are looking for seems to be solved by this query :
select
reason,
count(*)
from (select * from tablename group by name) abc
group by
reason
It is quite fast and simple. You can view the SQL Fiddle
Apologies if this answer duplicates an existing. Maybe I'm suffering from some form aphasia but I cannot see it...
SELECT x.reason
, COUNT(*)
FROM absentism x
JOIN
( SELECT name,MAX(date) max_date FROM absentism GROUP BY name) y
ON y.name = x.name
AND y.max_date = x.date
GROUP
BY reason;