This one is fairly specific, so I'm hoping for a quick fix.
I have a single result in my leaderboard table for each team. In my teams table, I have several results for each team (one result per game to enable team development history).
I want to show each team in the leaderboard once, and have teamID replaced by strName. Problem is, my left join is giving me one record for each team result; I just want a single record.
SELECT * , a.strName AS teamName
FROM bb_leaderboards l
LEFT JOIN bb_teams a ON ( l.teamID = a.ID )
WHERE l.season =8
AND l.division =1
ORDER BY l.division DESC , points DESC , wins DESC , l.TDdiff DESC
LIMIT 0 , 30
What do I need to do to this to get a 1:1 output?
You could do a SELECT DISTINCT instead, but you'll have to narrow down your select a bit. So:
SELECT DISTINCT l.*, a.strName AS teamName
...
That should filter out the duplicates.
Related
How I can get top 10 scorers by seasons.
So it shows last season top 10 scorers...
I've tryed left join into table, but it goes broken showing 2 player and counts all goals to first player.
My sqlfiddle:
http://sqlfiddle.com/#!9/b5d0a78/1
You got it almost right.
You want to group match_goals by player ID (match_player_id), but then you should not select goal_minute or any other per goal data.
After grouping by player, then you can create a column for COUNT(match_player_id) this will give you the number of goals, you can also use this column to order the results.
Your joins and conditions are correct I think.
EDIT
I think your schema needs a few tweaks: check this http://sqlfiddle.com/#!9/f5a75b/2
Basically create direct relations in the match_players and match_goals to the other tables.
I think the query you want looks like this:
SELECT p.*, count(*) as num_goals
FROM match_goals g INNER JOIN
match_players p
ON g.match_player_id = p.id INNER JOIN
matches m
ON m.id = p.match_id
WHERE p.is_deleted = 0 AND
g.is_own_goal = 0 AND
m.seasion_id = <last season id>
GROUP BY p.id
ORDER BY num_goals DESC
LIMIT 10;
Note that the teams table is not needed. The SELECT p.* is allowed because p.id (the GROUP BY key) is unique.
So i would like to make a toplist in mysql.
I have two table, users and teams.
In users I have: id,name,points,teamid
In teams I have: t_id,teamname,leaderid
I would like to make a toplist. The 10 teams with the most points.
I hope it is understandable what I want.
You need to calculate the total sum of points by using the subquery which will give you the top 10 points then join this result with a query which has team information with the sum of points for each team,from this approach if there is tie in scores of 2 teams they will be included in top 10 teams regarding the points
select t2.* from
(select t.*,sum(u.points) allpoints
from teams t
join users u
on(t.t_id= u.teamid)
group by t.t_id
) t2
join
(select sum(points) allpoints
from users
group by teamid
order by allpoints desc
limit 10) tp
on(t2.allpoints = tp.allpoints )
if you don't care for tie scenario you can simply use limit and order by
select t.*,sum(u.points) allpoints
from teams t
join users u
on(t.t_id= u.teamid)
group by t.t_id
order by allpoints desc
limit 10
I'm struggling a little with a query I'm trying to build. For a game I want to display the top 10 of scores.
My table looks like this:
player = id, playername, username
score = id, track, car, bestscore, totalscore, player_id (foreign key to player.id)
For the top10 I want to show the playername, the total score, the car and the track.
The current query I have is:
SELECT p.playername, MAX(s.totalscore) totalscore, s.car, s.track
FROM player p
INNER JOIN score s on p.id = s.player_id
GROUP BY p.playername
ORDER BY MAX(s.totalscore) DESC
LIMIT 10
This seems to work fine, except for one problem. If a user has a score of 50 on track 1 with car 1, and then puts a score of 60 on track 1 with car 2, I see car 1 on the query. It does not seem to get the according car of the top score if this user.
I hope it makes sense what I just told.
Thanks in advance!
EDIT:
SELECT p.playername, MAX(s.totalscore) as totalscore, s.car, s.track
FROM (SELECT * FROM score ORDER BY totalscore DESC) s
INNER JOIN player p ON s.player_id = p.id
GROUP BY p.playername
ORDER BY MAX(s.totalscore) DESC
LIMIT 10
This query seems to do the trick. I've been trying around and the result-set is exactly what I mean. Is it any good though? I'm not good at SQL and just because it works doesn't always mean it's good, does it?
When you have a non-aggregated field as part of an aggregated query that isn't in your group by, and has a many to one relationship with the relation on which you are grouping, MySQL gives no guarantee what it will return.
This query would throw an error in another RDBMS. If you care about the top score by (person,car) tuple, just add it to the group by. However, if you want each player to have a max score, regardless of what car was used, you'll need a subquery or a self join.
One way to do it:
SELECT p.playername, s1.totalscore , s1.car, s1.track
FROM player p
INNER JOIN
score s1 on p.id = s1.player_id
WHERE s1.totalscore = ( SELECT MAX(totalscore) FROM score s2 WHERE s2.player_id=s1.player_id)
ORDER BY s1.totalscore DESC
LIMIT 10
You use "Group By" on playername so the other columns will group in "what mysql desides" manner. If you want to get the cars you should add - group by car.
SELECT p.playername, MAX(s.totalscore) totalscore, s.car, s.track
FROM player p
INNER JOIN score s on p.id = s.player_id
GROUP BY p.playername, s.car //added car
ORDER BY s.totalscore DESC
LIMIT 10
I have 2 MYSQL tables, users and scores. Detail:
users table:
scores table:
My intention is get 20 users list that have point field sort DESC (descending) combine avg_time field sort ASC (ascending). I use the query:
SELECT users.username, scores.point, scores.avg_time
FROM scores, users
WHERE scores.user_id = users.id
GROUP BY users.username
ORDER BY scores.point DESC, scores.avg_time
LIMIT 0, 20
The result is:
The result is wrong because the first line is exactly point = 100 and avg_time = 60.
My desired result is:
username point avg_time
demo123 100 60
demo123456 100 100
demo 90 120
I tried many times with different queries but the result is still wrong. Could you give me some solutions?
Ok, I THINK I understand what you want now, and let me clarify to confirm before the query. You want 1 record for each user. For each user, you want their BEST POINTS score record. Of the best points per user, you want the one with the best average time. Once you have all users "best" values, you want the final results sorted with best points first... Almost like ranking of a competition.
So now the query. If the above statement is accurate, you need to start with getting the best point/average time per person and assigning a "Rank" to that entry. This is easily done using MySQL # variables. Then, just include a HAVING clause to only keep those records ranked 1 for each person. Finally apply the order by of best points and shortest average time.
select
U.UserName,
PreSortedPerUser.Point,
PreSortedPerUser.Avg_Time,
#UserRank := if( #lastUserID = PreSortedPerUser.User_ID, #UserRank +1, 1 ) FinalRank,
#lastUserID := PreSortedPerUser.User_ID
from
( select
S.user_id,
S.point,
S.avg_time
from
Scores S
order by
S.user_id,
S.point DESC,
S.Avg_Time ) PreSortedPerUser
JOIN Users U
on PreSortedPerUser.user_ID = U.ID,
( select #lastUserID := 0,
#UserRank := 0 ) sqlvars
having
FinalRank = 1
order by
Point Desc,
Avg_Time
Results as handled by SQLFiddle
Note, due to the inline #variables needed to get the answer, there are the two extra columns at the end of each row. These are just "left-over" and can be ignored in any actual output presentation you are trying to do... OR, you can wrap the entire thing above one more level to just get the few columns you want like
select
PQ.UserName,
PQ.Point,
PQ.Avg_Time
from
( entire query above pasted here ) as PQ
i think u miss understand about table relation..
users : scores = 1 : *
just join is not a solution.
is this your intention?
SELECT users.username, avg(scores.point), avg(scores.avg_time)
FROM scores, users
WHERE scores.user_id = users.id
GROUP BY users.username
ORDER BY avg(scores.point) DESC, avg(scores.avg_time)
LIMIT 0, 20
(this query to get each users average point and average avg_time by desc point, asc )avg_time
if you want to get each scores ranking? use left outer join
SELECT users.username, scores.point, scores.avg_time
FROM scores left outer join users on scores.user_id = users.id
ORDER BY scores.point DESC, scores.avg_time
LIMIT 0, 20
#DRapp is a genius. I never understood how he coded his SQL,so I tried coding it in my own understanding.
SELECT
f.username,
f.point,
f.avg_time
FROM
(
SELECT
userscores.username,
userscores.point,
userscores.avg_time
FROM
(
SELECT
users.username,
scores.point,
scores.avg_time
FROM
scores
JOIN users
ON scores.user_id = users.id
ORDER BY scores.point DESC
) userscores
ORDER BY
point DESC,
avg_time
) f
GROUP BY f.username
ORDER BY point DESC
It yields the same result by using GROUP BY instead of the user #variables.
group by default order by pk id，so the result
username point avg_time
demo123 100 90 ---> id = 4
demo123456 100 100 ---> id = 7
demo 90 120 ---> id = 1
I have these tables and queries as defined in sqlfiddle.
First my problem was to group people showing LEFT JOINed visits rows with the newest year. That I solved using subquery.
Now my problem is that that subquery is not using INDEX defined on visits table. That is causing my query to run nearly indefinitely on tables with approx 15000 rows each.
Here's the query. The goal is to list every person once with his newest (by year) record in visits table.
Unfortunately on large tables it gets real sloooow because it's not using INDEX in subquery.
SELECT *
FROM people
LEFT JOIN (
SELECT *
FROM visits
ORDER BY visits.year DESC
) AS visits
ON people.id = visits.id_people
GROUP BY people.id
Does anyone know how to force MySQL to use INDEX already defined on visits table?
Your query:
SELECT *
FROM people
LEFT JOIN (
SELECT *
FROM visits
ORDER BY visits.year DESC
) AS visits
ON people.id = visits.id_people
GROUP BY people.id;
First, is using non-standard SQL syntax (items appear in the SELECT list that are not part of the GROUP BY clause, are not aggregate functions and do not sepend on the grouping items). This can give indeterminate (semi-random) results.
Second, ( to avoid the indeterminate results) you have added an ORDER BY inside a subquery which (non-standard or not) is not documented anywhere in MySQL documentation that it should work as expected. So, it may be working now but it may not work in the not so distant future, when you upgrade to MySQL version X (where the optimizer will be clever enough to understand that ORDER BY inside a derived table is redundant and can be eliminated).
Try using this query:
SELECT
p.*, v.*
FROM
people AS p
LEFT JOIN
( SELECT
id_people
, MAX(year) AS year
FROM
visits
GROUP BY
id_people
) AS vm
JOIN
visits AS v
ON v.id_people = vm.id_people
AND v.year = vm.year
ON v.id_people = p.id;
The: SQL-fiddle
A compound index on (id_people, year) would help efficiency.
A different approach. It works fine if you limit the persons to a sensible limit (say 30) first and then join to the visits table:
SELECT
p.*, v.*
FROM
( SELECT *
FROM people
ORDER BY name
LIMIT 30
) AS p
LEFT JOIN
visits AS v
ON v.id_people = p.id
AND v.year =
( SELECT
year
FROM
visits
WHERE
id_people = p.id
ORDER BY
year DESC
LIMIT 1
)
ORDER BY name ;
Why do you have a subquery when all you need is a table name for joining?
It is also not obvious to me why your query has a GROUP BY clause in it. GROUP BY is ordinarily used with aggregate functions like MAX or COUNT, but you don't have those.
How about this? It may solve your problem.
SELECT people.id, people.name, MAX(visits.year) year
FROM people
JOIN visits ON people.id = visits.id_people
GROUP BY people.id, people.name
If you need to show the person, the most recent visit, and the note from the most recent visit, you're going to have to explicitly join the visits table again to the summary query (virtual table) like so.
SELECT a.id, a.name, a.year, v.note
FROM (
SELECT people.id, people.name, MAX(visits.year) year
FROM people
JOIN visits ON people.id = visits.id_people
GROUP BY people.id, people.name
)a
JOIN visits v ON (a.id = v.id_people and a.year = v.year)
Go fiddle: http://www.sqlfiddle.com/#!2/d67fc/20/0
If you need to show something for people that have never had a visit, you should try switching the JOIN items in my statement with LEFT JOIN.
As someone else wrote, an ORDER BY clause in a subquery is not standard, and generates unpredictable results. In your case it baffled the optimizer.
Edit: GROUP BY is a big hammer. Don't use it unless you need it. And, don't use it unless you use an aggregate function in the query.
Notice that if you have more than one row in visits for a person and the most recent year, this query will generate multiple rows for that person, one for each visit in that year. If you want just one row per person, and you DON'T need the note for the visit, then the first query will do the trick. If you have more than one visit for a person in a year, and you only need the latest one, you have to identify which row IS the latest one. Usually it will be the one with the highest ID number, but only you know that for sure. I added another person to your fiddle with that situation. http://www.sqlfiddle.com/#!2/4f644/2/0
This is complicated. But: if your visits.id numbers are automatically assigned and they are always in time order, you can simply report the highest visit id, and be guaranteed that you'll have the latest year. This will be a very efficient query.
SELECT p.id, p.name, v.year, v.note
FROM (
SELECT id_people, max(id) id
FROM visits
GROUP BY id_people
)m
JOIN people p ON (p.id = m.id_people)
JOIN visits v ON (m.id = v.id)
http://www.sqlfiddle.com/#!2/4f644/1/0 But this is not the way your example is set up. So you need another way to disambiguate your latest visit, so you just get one row per person. The only trick we have at our disposal is to use the largest id number.
So, we need to get a list of the visit.id numbers that are the latest ones, by this definition, from your tables. This query does that, with a MAX(year)...GROUP BY(id_people) nested inside a MAX(id)...GROUP BY(id_people) query.
SELECT v.id_people,
MAX(v.id) id
FROM (
SELECT id_people,
MAX(year) year
FROM visits
GROUP BY id_people
)p
JOIN visits v ON (p.id_people = v.id_people AND p.year = v.year)
GROUP BY v.id_people
The overall query (http://www.sqlfiddle.com/#!2/c2da2/1/0) is this.
SELECT p.id, p.name, v.year, v.note
FROM (
SELECT v.id_people,
MAX(v.id) id
FROM (
SELECT id_people,
MAX(year) year
FROM visits
GROUP BY id_people
)p
JOIN visits v ON ( p.id_people = v.id_people
AND p.year = v.year)
GROUP BY v.id_people
)m
JOIN people p ON (m.id_people = p.id)
JOIN visits v ON (m.id = v.id)
Disambiguation in SQL is a tricky business to learn, because it takes some time to wrap your head around the idea that there's no inherent order to rows in a DBMS.