I have a these tables
USERS
+----------+---------------+
| id_users | usr_email |
+----------+---------------+
| 1 | a#domain.com |
| 2 | b#domain.com |
| 3 | c#domain.com |
| 4 | d#domain.com |
| 5 | e#domain.com |
+----------+---------------+
RANKING
+-------------+-----------+----------+
| id_ranking | id_users | points |
+-------------+-----------+----------+
| 50 | 1 | 27 | //3rd
| 51 | 2 | 55 | //1st
| 52 | 3 | 9 | //5th
| 53 | 4 | 14 | //4th
| 54 | 5 | 38 | //2nd
+-------------+-----------+----------+
I would like to retireve user's data along with it's ranking position, filtering by e-mail. So for example if I want info for mail c#domain.com I should get
+----------+--------|---------------+
| id_users | points | rank_position |
+----------+--------|---------------+
| 3 | 9 | 5 |
+----------+--------|---------------+
I've found this piece of query that returns the ranking position
SELECT x.id_users, x.position
FROM (
SELECT t1.id_ranking, t1.id_users, #rownum := #rownum + 1 AS position
FROM ranking t1
JOIN (SELECT #rownum := 0) r ORDER BY t1.points desc
) x
WHERE x.id_users = 3
But I can't manage to use it in my old query
select u.*, r.points
from users u
left join ranking r on r.id_users = u.id_users
where u.usr_email = 'c#domain.com'
My attemp
select u.*, r.points, p.*
from users u
left join ranking r on r.id_users = u.id_users,
(SELECT x.id_users, x.position
FROM (
SELECT t1.id_ranking, t1.id_users, #rownum := #rownum + 1 AS position
FROM ranking t1
JOIN (SELECT #rownum := 0) r ORDER BY t1.points desc
) x
WHERE x.id_users = u.id_users) p
where u.usr_email = 'c#domain.com'
Any help?
You are missing a join condition. But also, the outer join to ranking is not necessary. You can "remember" the points in the subquery:
select u.*, r.points, r.position
from users u left join
(select r.*, #rownum := #rownum + 1 AS position
from ranking r CROSS JOIN
(SELECT #rownum := 0) r
order by r.points desc
) r
ON r.id_users = u.id_users
where u.usr_email = 'c#domain.com'
select u.id_users,
r.points,
count(ifnull(r2.id_users, 0)) + 1 as rank_position
from users u
join ranking r
on u.id_users = r.id_users
left join ranking r2
on r2.points > r.points
where u.usr_email = 'c#domain.com'
group by u.id_users, r.points
Fiddle: http://sqlfiddle.com/#!2/1444e8/1/0
Rather than a variable this counts the number of users who have more points than the given user, and then adds one. This is an equivalent way of calculating their rank, in terms of number of points.
Related
I want to find a user's position in a leaderboard and return the 4 users above and 4 users below their position.
My table, 'predictions', looks something like this:
+----+---------+--------+-------+---------+
| id | userId | score | rank | gameId |
+----+---------+--------+-------+---------+
| 1 | 12 | 11 | 1 | 18 |
| 2 | 1 | 6 | 4 | 18 |
| 3 | 43 | 7 | 3 | 12 |
| 4 | 4 | 9 | 2 | 18 |
| 5 | 98 | 2 | 5 | 19 |
| 6 | 3 | 0 | 6 | 18 |
+----+---------+--------+-------+---------+
Obviously this isn't properly ordered, so I run this:
SELECT l.userId,
l.rank,
l.score,
l.createdAt,
#curRow := #curRow + 1 AS row_number
FROM (SELECT * FROM `predictions` WHERE gameId = 18) l
JOIN (SELECT #curRow := 0) r
ORDER BY rank ASC
which gets me a nice table with each entry numbered.
I then want to search this generated table, find the row_number where userId = X, and then return the values 'around' that result.
I think I have the logic of the query down, I just can't work out how to reference the table 'generated' by the above query.
It would be something like this:
SELECT *
FROM (
SELECT l.userId,
l.rank,
l.score,
l.createdAt,
#curRow := #curRow + 1 AS row_number
FROM (SELECT * FROM `predictions` WHERE gameId = 18) l
JOIN (SELECT #curRow := 0) r
ORDER BY rank ASC) generated_ordered_table
WHERE row_number < (SELECT row_number FROM generated_ordered_table WHERE userId = 1)
ORDER BY row_number DESC
LIMIT 0,5
This fails. What I'm trying to do is to generate my first table with the correct query, give it an alias of generated_ordered_table, and then reference this 'table' later on in this query.
How do I do this?
MySQL version 8+ could have allowed the usage of Window functions, and Common Table Expressions (CTEs); which would have simplified the query quite a bit.
Now, in the older versions (your case), the "Generated Rank Table" (Derived Table) cannot be referenced again in a subquery inside the WHERE clause. One way would be to do the same thing twice (select clause to get generated table) again inside the subquery, but that would be relatively inefficient.
So, another approach can be to use Temporary Tables. We create a temp table first storing the ranks. And, then reference that temp table to get results accordingly:
CREATE TEMPORARY TABLE IF NOT EXISTS gen_rank_tbl AS
(SELECT l.userId,
l.rank,
l.score,
l.createdAt,
#curRow := #curRow + 1 AS row_number
FROM (SELECT * FROM `predictions` WHERE gameId = 18) l
JOIN (SELECT #curRow := 0) r
ORDER BY rank ASC)
Now, you can reference this temp table to get the desired results:
SELECT *
FROM gen_rank_tbl
WHERE row_number < (SELECT row_number FROM gen_rank_tbl WHERE userId = 1)
ORDER BY row_number DESC
LIMIT 0,5
You could use a bunch of unions
select userid,rank,'eq'
from t where gameid = 18 and userid = 1
union
(
select userid,rank,'lt'
from t
where gameid = 18 and rank < (select rank from t t1 where t1.userid = 1 and t1.gameid = t.gameid)
order by rank desc limit 4
)
union
(
select userid,rank,'gt'
from t
where gameid = 18 and rank > (select rank from t t1 where t1.userid = 1 and t1.gameid = t.gameid)
order by rank desc limit 4
);
+--------+------+----+
| userid | rank | eq |
+--------+------+----+
| 1 | 4 | eq |
| 4 | 2 | lt |
| 12 | 1 | lt |
| 3 | 6 | gt |
+--------+------+----+
4 rows in set (0.04 sec)
But it's not pretty
You can use two derived tables:
SELECT p.*,
(#user_curRow = CASE WHEN user_id = #x THEN rn END) as user_rn
FROM (SELECT p.*, #curRow := #curRow + 1 AS rn
FROM (SELECT p.*
FROM predictions p
WHERE p.gameId = 18
ORDER BY rank ASC
) p CROSS JOIN
(SELECT #curRow := 0, #user_curRow := -1) params
) p
HAVING rn BETWEEN #user_curRow - 4 AND #user_currow + 4;
Let's assume I have two columns: letters and numbers in a table called tbl;
letters numbers
a 1
b 2
c 3
d 4
Doing a cartesian product will lead to :
a 1
a 2
a 3
a 4
b 1
b 2
b 3
b 4
c 1
c 2
c 3
c 4
d 1
d 2
d 3
d 4
Write a query that reverts the cartesian product of these two columns back to the original table.
I tried multiple methods from using ROWNUM to selecting distinct values and joining them (which leads me back to the cartesian product)
SELECT DISTINCT *
FROM (SELECT DISTINCT NUMBERS
FROM TBL
ORDER BY NUMBERS) AS NB
JOIN (SELECT DISTINCT LETTERS
FROM TBL
ORDER BY LETTERS) AS LT1
which led me back to the cartesian product....
This is a version that works with 5.7.
SELECT `numbers`,`letters` FROM
(SELECT `numbers`,
#curRank := #curRank + 1 AS rank
FROM Table1 t, (SELECT #curRank := 0) r
GROUP By `numbers`
ORDER BY `numbers`) NB1
INNER JOIN
(SELECT `letters`,
#curRank1 := #curRank1 + 1 AS rank
FROM (
Select `letters` FROM Table1 t
GROUP By `letters`) t2, (SELECT #curRank1 := 0) r
ORDER BY `letters`) LT1 ON NB1.rank = LT1.rank;
https://dbfiddle.uk/?rdbms=mysql_5.7&fiddle=cc17c2cfeff049edc73e437e5e4fd892
As Raymond and Ankit pointed out you have to know which order have the letters and even the order of the numbers has to be defined prior or else you never get a correct answer.
Another way of writing this:
SELECT numbers
, letters
FROM
( SELECT DISTINCT numbers
, #curRank := #curRank + 1 rank
FROM Table1 t
, (SELECT #curRank := 0) r
ORDER
BY numbers
) NB1
JOIN
( SELECT letters
, #curRank1 := #curRank1 + 1 rank
FROM
( SELECT DISTINCT letters
FROM Table1 t
) t2
, (SELECT #curRank1 := 0) r
ORDER
BY letters
) LT1
ON NB1.rank = LT1.rank;
If you are sure that the order will never be destroyed and is deterministic, You can use dense_rank() analytic function to achieve it back -
SELECT LT1.LETTERS, NB.NUMBERS
FROM (SELECT DISTINCT NUMBERS
FROM TBL
ORDER BY NUMBERS) AS NB
JOIN (SELECT DISTINCT LETTERS, RN
FROM (SELECT LETTERS, DENSE_RANK() OVER (ORDER BY LETTERS) RN
FROM TBL
ORDER BY LETTERS) T) AS LT1
ON NB.NUMBERS = LT1.RN
Here is the fiddle
Perhaps this is oversimplifying the problem, but it should be seen that this, or some variation of it, would suffice...
SELECT * FROM my_table;
+---------+---------+
| letters | numbers |
+---------+---------+
| a | 1 |
| a | 2 |
| a | 3 |
| a | 4 |
| b | 1 |
| b | 2 |
| b | 3 |
| b | 4 |
| c | 1 |
| c | 2 |
| c | 3 |
| c | 4 |
| d | 1 |
| d | 2 |
| d | 3 |
| d | 4 |
+---------+---------+
16 rows in set (0.00 sec)
SELECT x.*
, #i:=#i+1 numbers
FROM
( SELECT DISTINCT letters
FROM my_table
) x
, (SELECT #i:=0) vars
ORDER
BY letters;
+---------+---------+
| letters | numbers |
+---------+---------+
| a | 1 |
| b | 2 |
| c | 3 |
| d | 4 |
+---------+---------+
I'm creating rank system so I need to set rank position for every user.
I do this:
SELECT #curRow := #curRow + 1 AS position,
Sum(point_user.amount) AS points
FROM users u
JOIN point_user ON u.id = point_user.user_id
JOIN (SELECT #curRow := 0) r
GROUP BY
u.id
ORDER BY
position ASC
And I'm getting:
+----------+----------+
| position | points |
+----------+----------+
| 1 | 86 |
| 2 | 239 |
| 3 | 45 |
+----------+----------+
Now, how can I set row number, based on points?
Should looks like:
+----------+----------+
| position | points |
+----------+----------+
| 1 | 239 |
| 2 | 86 |
| 3 | 45 |
+----------+----------+
UPDATE
SELECT (#curRow := #curRow + 1) as position,
points,
u2.id
FROM (SELECT Sum(pu.amount) AS points
FROM users u JOIN
point_user pu
ON u.id = pu.user_id
GROUP BY u.id
ORDER BY points DESC
) upu, users u2
CROSS JOIN (
SELECT #curRow := 0
) params
ORDER BY points DESC
In your query, it might be sufficient to change the ORDER BY to ORDER BY points DESC -- because that seems to be your intention.
However, MySQL has a known problem with variables and GROUP BY. The solution is simply to use a subquery:
SELECT (#curRow := #curRow + 1) as position, points
FROM (SELECT Sum(pu.amount) AS points
FROM users u JOIN
point_user pu
ON u.id = pu.user_id
GROUP BY u.id
ORDER BY points DESC
) upu CROSS JOIN
(SELECT #curRow := 0) params
ORDER BY points DESC;
My table
+------+-------+--------+
| NAME | MARKS | POINTS |
+------+-------+--------+
| S1 | 53 | (null) |
| S2 | 55 | (null) |
| S3 | 56 | (null) |
| S4 | 55 | (null) |
| S5 | 52 | (null) |
| S6 | 51 | (null) |
| S7 | 53 | (null) |
+------+-------+--------+
Refer : http://www.sqlfiddle.com/#!2/5d046/1
I would like to add 3,2,1 points to the highest Marks. Here S3 goes to 3 points, S2,S4 goes to 2 points and S1,S7 goes to 1 points.
Final outputs looks,
+------+-------+--------+
| NAME | MARKS | POINTS |
+------+-------+--------+
| S1 | 53 | 1 |
| S2 | 55 | 2 |
| S3 | 56 | 3 |
| S4 | 55 | 2 |
| S5 | 52 | 0 |
| S6 | 51 | 0 |
| S7 | 53 | 1 |
+------+-------+--------+
Plz help
My suggestion is that you first calculate the ranking of each mark, and then use that in a case statement in an update.
The following query shows one way to calculate the ranking:
select t.*,
#rn := if(#marks = marks, #rn, #rn + 1) as ranking,
#marks := marks
from myTable t cross join
(select #rn := 0, #marks := -1) const
order by t.marks desc;
(As a note: I am a bit uncomfortable with this method, because MySQL does not guarantee the order of evaluation of the two expressions with constants. If #marks were set before #rn, then it wouldn't work. In practice, that does not seem to happen. And, this is more efficient that the equivalent with a correlated subquery.)
You can then put this into an update using join:
update myTable join
(select t.*,
#rn := if(#marks = marks, #rn, #rn + 1) as ranking,
#marks := marks
from myTable t cross join
(select #rn := 0, #marks := -1) const
order by t.marks desc
) mr
on myTable.Name = mr.Name
set myTable.Points := (case when mr.ranking = 1 then 3
when mr.ranking = 2 then 2
when mr.ranking = 3 then 1
else 0
end);
This has been tested on your SQL Fiddle.
You can do it via variables (see samples in other answers), or via case:
select
myTable.*,
case
when max1.marks is not null then 3
when max2.marks is not null then 2
when max3.marks is not null then 1
else 0
end as score
from
myTable
LEFT JOIN
(select marks from myTable order by marks desc limit 1) AS max1
ON myTable.marks=max1.marks
LEFT JOIN
(select marks from myTable order by marks desc limit 2,1) AS max2
ON myTable.marks=max2.marks
LEFT JOIN
(select marks from myTable order by marks desc limit 3,1) AS max3
ON myTable.marks=max3.marks;
the demo can be found here.
UPDATE myTable t1
INNER JOIN
(
SELECT #row:=#row-1 AS RowPoints, Marks
FROM (
SELECT Marks
FROM myTable
GROUP BY Marks
ORDER BY Marks DESC
LIMIT 3
) AS TopMarks
INNER JOIN (SELECT #row:=4) AS RowInit
) AS AddPoints ON t1.Marks = AddPoints.Marks
SET Points = COALESCE(Points, 0) + AddPoints.RowPoints;
This should work just fine. You should and and index on the Marks column.
The simplest way to do this:
SELECT t.Name Name, t.Marks Marks,
(CASE WHEN Marks = (Select max(marks) from mytable) THEN 3 ELSE 0 END+
CASE WHEN Marks = (Select min(marks) from (Select distinct marks
from mytable order by marks desc limit 2) a) THEN 2 ELSE 0 END+
CASE WHEN Marks = (Select min(marks) from (Select distinct marks
from mytable order by marks desc limit 3) b) THEN 1 ELSE 0 END)
AS `Points`
FROM mytable t;
SQL Fiddle
I have a table in mySql which has the users ID and scores.
What I would like to do is organise the table by scores (simple) but then find where a certain user ID sits in the table.
So far I would have:
SELECT * FROM table_score
ORDER BY Score DESC
How would I find where userID = '1234' is (i.e entry 10 of 12)
The following query will give you a new column UserRank, which specify the user rank:
SELECT
UserID,
Score,
(#rownum := #rownum + 1) UserRank
FROM table_score, (SELECT #rownum := 0) t
ORDER BY Score DESC;
SQL Fiddle Demo
This will give you something like:
| USERID | SCORE | USERRANK |
-----------------------------
| 4 | 100 | 1 |
| 10 | 70 | 2 |
| 2 | 55 | 3 |
| 1234 | 50 | 4 |
| 1 | 36 | 5 |
| 20 | 33 | 6 |
| 8 | 25 | 7 |
Then you can put this query inside a subquery and filter with a userId to get that user rank. Something like:
SELECT
t.UserRank
FROM
(
SELECT *, (#rownum := #rownum + 1) UserRank
FROM table_score, (SELECT #rownum := 0) t
ORDER BY Score DESC
) t
WHERE userID = '1234';
SQL Fiddle Demo
For a given user id, you can do this with a simple query:
select sum(case when ts.score >= thescore.score then 1 else 0 end) as NumAbove,
count(*) as Total
from table_score ts cross join
(select ts.score from table_score ts where userId = '1234') thescore
If you have indexes on score and userid, this will be quite efficient.