i'm creating a Rock Papper Scisors game, the problem that i'm facing is that i need to set a winner based on a Best Of 3, 5 or 7, and to do so i need to calculate the number of consecutive querys my bet table is simple:
BO3
ID|GAME_ID|WINNER
1 |145 |15
2 |145 |14
3 |145 |15
4 |145 |15
15 needs to win , how can i calculate it in mysql?
ex:
GAME_ID|WINNER|CONSECUTIVES
145|15 |2
Thanks a lot.
I think you are going to need variables for this:
select gameid, winner, max(rn)
from (select s.*,
(#rn := if(#gw = concat_ws(':', gameid, winner), #rn + 1,
if(#gw := concat_ws(':', gameid, winner), 1, 1)
)
) as rn
from scores s cross join
(select #gw := '', #rn := 0) params
order by s.id
) s
group by gameid, winner;
Here is a SQL Fiddle.
Maybe something like this:
select y.winner,
case when y2.cnt <= 3 then 'Best of 3'
when y2.cnt <= 5 then 'Best of 5'
when y2.cnt <= 7 then 'Best of 7'
end, count(*)
from yourtable y join (
select count(*) cnt, gameid
from yourtable
group by gameid) y2 on y.gameid = y2.gameid
group by y.gameid, y.winner, y2.cnt
having count(*) = 2 and y2.cnt <= 3 or
count(*) = 3 and y2.cnt <= 5 or
count(*) = 4 and y2.cnt <= 7
SQL Fiddle Demo
Related
So I was taking a test recently with some higher level SQL problems. I only have what I would consider "intermediate" experience in SQL and I've been working on this for a day or so now. I just can't figure it out.
Here's the problem:
You have a table with 4 columns as such:
EmployeeID int unique
EmployeeType int
EmployeeSalary int
Created date
Goal: I need to retrieve the difference between the latest two EmployeeSalary for any EmployeeType with more than 1 entry. It has to be done in one statement (nested queries are fine).
Example Data Set: http://sqlfiddle.com/#!9/0dfc7
EmployeeID | EmployeeType | EmployeeSalary | Created
-----------|--------------|----------------|--------------------
1 | 53 | 50 | 2015-11-15 00:00:00
2 | 66 | 20 | 2014-11-11 04:20:23
3 | 66 | 30 | 2015-11-03 08:26:21
4 | 66 | 10 | 2013-11-02 11:32:47
5 | 78 | 70 | 2009-11-08 04:47:47
6 | 78 | 45 | 2006-11-01 04:42:55
So for this data set, the proper return would be:
EmployeeType | EmployeeSalary
-------------|---------------
66 | 10
78 | 25
The 10 comes from subtracting the latest two EmployeeSalary values (30 - 20) for the EmployeeType of 66. The 25 comes from subtracting the latest two EmployeeSalary values (70-45) for EmployeeType of 78. We skip EmployeeID 53 completely because it only has one value.
This one has been destroying my brain. Any clues?
Thanks!
How to make really simple query complex?
One funny way(not best performance) to do it is:
SELECT final.EmployeeType, SUM(salary) AS difference
FROM (
SELECT b.EmployeeType, b.EmployeeSalary AS salary
FROM tab b
JOIN (SELECT EmployeeType, GROUP_CONCAT(EmployeeSalary ORDER BY Created DESC) AS c
FROM tab
GROUP BY EmployeeType
HAVING COUNT(*) > 1) AS sub
ON b.EmployeeType = sub.EmployeeType
AND FIND_IN_SET(b.EmployeeSalary, sub.c) = 1
UNION ALL
SELECT b.EmployeeType, -b.EmployeeSalary AS salary
FROM tab b
JOIN (SELECT EmployeeType, GROUP_CONCAT(EmployeeSalary ORDER BY Created DESC) AS c
FROM tab
GROUP BY EmployeeType
HAVING COUNT(*) > 1) AS sub
ON b.EmployeeType = sub.EmployeeType
AND FIND_IN_SET(b.EmployeeSalary, sub.c) = 2
) AS final
GROUP BY final.EmployeeType;
SqlFiddleDemo
EDIT:
The keypoint is MySQL doesn't support windowed function so you need to use equivalent code:
For example solution in SQL Server:
SELECT EmployeeType, SUM(CASE rn WHEN 1 THEN EmployeeSalary
ELSE -EmployeeSalary END) AS difference
FROM (SELECT *,
ROW_NUMBER() OVER(PARTITION BY EmployeeType ORDER BY Created DESC) AS rn
FROM #tab
) AS sub
WHERE rn IN (1,2)
GROUP BY EmployeeType
HAVING COUNT(EmployeeType) > 1
LiveDemo
And MySQL equivalent:
SELECT EmployeeType, SUM(CASE rn WHEN 1 THEN EmployeeSalary
ELSE -EmployeeSalary END) AS difference
FROM (
SELECT t1.EmployeeType, t1.EmployeeSalary,
count(t2.Created) + 1 as rn
FROM #tab t1
LEFT JOIN #tab t2
ON t1.EmployeeType = t2.EmployeeType
AND t1.Created < t2.Created
GROUP BY t1.EmployeeType, t1.EmployeeSalary
) AS sub
WHERE rn IN (1,2)
GROUP BY EmployeeType
HAVING COUNT(EmployeeType) > 1;
LiveDemo2
The dataset of the fiddle is different from the example above, which is confusing (not to mention a little perverse). Anyway, there's lots of ways to skin this particular cat. Here's one (not the fastest, however):
SELECT a.employeetype, ABS(a.employeesalary-b.employeesalary) diff
FROM
( SELECT x.*
, COUNT(*) rank
FROM employees x
JOIN employees y
ON y.employeetype = x.employeetype
AND y.created >= x.created
GROUP
BY x.employeetype
, x.created
) a
JOIN
( SELECT x.*
, COUNT(*) rank
FROM employees x
JOIN employees y
ON y.employeetype = x.employeetype
AND y.created >= x.created
GROUP
BY x.employeetype
, x.created
) b
ON b.employeetype = a.employeetype
AND b.rank = a.rank+1
WHERE a.rank = 1;
a very similar but faster solution looks like this (although you sometimes need to assign different variables between tables a and b - for reasons I still don't fully understand)...
SELECT a.employeetype
, ABS(a.employeesalary-b.employeesalary) diff
FROM
( SELECT x.*
, CASE WHEN #prev = x.employeetype THEN #i:=#i+1 ELSE #i:=1 END i
, #prev := x.employeetype prev
FROM employees x
, (SELECT #prev := 0, #i:=1) vars
ORDER
BY x.employeetype
, x.created DESC
) a
JOIN
( SELECT x.*
, CASE WHEN #prev = x.employeetype THEN #i:=#i+1 ELSE #i:=1 END i
, #prev := x.employeetype prev
FROM employees x
, (SELECT #prev := 0, #i:=1) vars
ORDER
BY x.employeetype
, x.created DESC
) b
ON b.employeetype = a.employeetype
AND b.i = a.i + 1
WHERE a.i = 1;
Table has aggregated values but i need to return multiple rows if the value is greater than one.
Here is how the table looks now:
date description amount
1/1/2015 alpha 3
1/1/2015 beta 1
Here is how i need it to return:
date description amount
1/1/2015 alpha 1
1/1/2015 alpha 1
1/1/2015 alpha 1
1/1/2015 beta 1
Any help would be greatly appreciated.
You need a table of numbers. Something like this works for up to 3 and can be easily extended:
select t.date, t.description, 1 as amount
from table t join
(select 1 as n union all select 2 union all select 3) n
on n.n <= t.amount;
EDIT:
If you have enough rows in the table for the larger amounts, you can do:
select t.date, t.description, 1 as amount
from table t join
(select #rn := #rn + 1 as n
from table cross join (select #rn := 0) vars
) n
on n.n <= t.amount;
This worked perfectly.
select t.date, t.description, 1 as amount
from table t join
(select #rn := #rn + 1 as n
from table cross join (select #rn := 0) vars
) n
on n.n <= t.amount;
I've the following table structure:
id |name |date
1 a 2012-01-01
2 a 2011-01-01
3 a 2010-01-01
4 a 2014-01-01
5 a 2011-01-01
I'd like to perform a select order by date (desc), and after select the first 3 rows from the results by a condition which would be where id = 1. So the second part of the query would be "give me the first 3 rows starting from the row whose id equals to 1"
EDIT:
After the first "part" the result would be:
SELECT id, name, date FROM table ORDER BY date DESC
id |name |date
4 a 2014-01-01
1 a 2012-01-01
2 a 2011-01-01
5 a 2011-01-01
3 a 2010-01-01
After the second part it should look like this (so the first 3 after the row whose id is 1):
id |name |date
2 a 2011-01-01
5 a 2011-01-01
3 a 2010-01-01
I have no any idea how could I solve it, please help me.
EDIT:
This is the concrete code I'd like to re-write:
SELECT `id`, `questions`.`userid`, `categories`.`name`, `user`.`username`, `title`,
`details`, `date` FROM `questions`
LEFT JOIN `user`
ON `questions`.`userid` = `user`.`userid`
LEFT JOIN `categories`
ON `questions`.`categoryid` = `categories`.`categoryid`
ORDER BY `date` DESC LIMIT 10
SELECT *
FROM table
WHERE date < (SELECT date FROM table WHERE id = 1)
ORDER BY date DESC
LIMIT 3
This isn't pretty because MySQL doesn't support row_number() or common table expressions, but it should work. Basically, get the row number ordered by the date, then select those whose row number is greater than an arbitrary value (in this case 1). Finally use limit to select the number of records you want.
SELECT id, name, mydate
FROM (
SELECT id, name, mydate, #rn:=#rn+1 rn
FROM mytable, (select #rn:=0) t
ORDER BY mydate DESC
) t2
WHERE rn > (
select rn
from (
SELECT id, name, mydate, #rn:=#rn+1 rn
FROM mytable, (select #rn:=0) t
ORDER BY mydate DESC
) t2
where id = 1
)
LIMIT 3
SQL Fiddle Demo
This is what you want to do... if finds the first id thats equal to 4 and then selects those out. then limit the offset to go to the next row and pull out 3
SELECT id, name, m_date from(
SELECT id, name, m_date, #a := id, if(#a = 4, #b := 1, #b) AS join_id
FROM test
join(SELECT #a := 0, #b := 0) t
ORDER BY m_date DESC
) AS tt
WHERE join_id = 1
LIMIT 1,3
SELECT temp.`id`, temp.`userid`, `categories`.`name`, `user`.`username`, temp.`title`,
temp.`details`, temp.`date` FROM (
SELECT `id`, `categoryid`, `details`, `title`, `userid`, `date`, #a := id, if(#a = 11, #b := 1, #b) AS join_id
FROM `questions`
join(SELECT #a := 0, #b := 0) t
ORDER BY `date` DESC
) as temp
LEFT JOIN `user`
ON temp.`userid` = `user`.`userid`
LEFT JOIN `categories`
ON temp.`categoryid` = `categories`.`categoryid`
WHERE join_id = 1
LIMIT 1,10;
SEE FIDDLE for clarification
I have a table that contains categories, dates and rates. Each category can have different rates for different dates, one category can have only one rate at a given date.
Id CatId Date Rate
------ ------ ------------ ---------
000001 12 2009-07-07 1
000002 12 2009-07-08 1
000003 12 2009-07-09 1
000004 12 2009-07-10 2
000005 12 2009-07-15 1
000006 12 2009-07-16 1
000007 13 2009-07-08 1
000008 13 2009-07-09 1
000009 14 2009-07-07 2
000010 14 2009-07-08 1
000010 14 2009-07-10 1
Unique index (catid, Date, Rate)
I would like for each category to group all continuous dates ranges and keep only the begin and the end of the range.
For the previous example, we would have:
CatId Begin End Rate
------ ------------ ------------ ---------
12 2009-07-07 2009-07-09 1
12 2009-07-10 2009-07-10 2
12 2009-07-15 2009-07-16 1
13 2009-07-08 2009-07-09 1
14 2009-07-07 2009-07-07 2
14 2009-07-08 2009-07-08 1
14 2009-07-10 2009-07-10 1
I found a similar solution in the forum which did not exactly give the result
WITH q AS
(
SELECT *,
ROW_NUMBER() OVER (PARTITION BY CatId, Rate ORDER BY [Date]) AS rnd,
ROW_NUMBER() OVER (PARTITION BY CatId ORDER BY [Date]) AS rn
FROM my_table
)
SELECT CatId AS catidd, MIN([Date]) as beginn, MAX([Date])as endd, Rate
FROM q
GROUP BY CatId, rnd - rn, Rate
SEE SQL FIDDLE
How can I do the same thing in mysql?
Please help!
MySQL doesn't support analytic functions, but you can emulate such behaviour with user-defined variables:
SELECT CatID, Begin, MAX(Date) AS End, Rate
FROM (
SELECT my_table.*,
#f:=CONVERT(
IF(#c<=>CatId AND #r<=>Rate AND DATEDIFF(Date, #d)=1, #f, Date), DATE
) AS Begin,
#c:=CatId, #d:=Date, #r:=Rate
FROM my_table JOIN (SELECT #c:=NULL) AS init
ORDER BY CatId, Rate, Date
) AS t
GROUP BY CatID, Begin, Rate
See it on sqlfiddle.
SELECT catid,min(ddate),max(ddate),rate
FROM (
SELECT
Catid,
Ddate,
rate,
#rn := CASE WHEN (#prev <> rate
or DATEDIFF(ddate, #prev_date)>1) THEN #rn+1 ELSE #rn END AS rn,
#prev := rate,
#prev_id := catid ,
#prev_date :=ddate
FROM (
SELECT CatID,Ddate,rate
FROM rankdate
ORDER BY CatID, Ddate ) AS a ,
(SELECT #prev := -1, #rn := 0, #prev_id:=0 ,#prev_date:=-1) AS vars
) T1 group by catid,rn
Note: The line (SELECT #prev := -1, #rn := 0, #prev_id:=0 ,#prev_date:=-1) AS vars is not necessary in Mysql Workspace, but it is in the PHP mysql_query function.
SQL FIDDLE HERE
I know I am late, still posting a solution that worked for me.
Had the same issue, here's how I got it
Found a good solution using variables
SELECT MIN(id) AS id, MIN(date) AS date, MIN(state) AS state, COUNT(*) cnt
FROM (
SELECT #r := #r + (#state != state OR #state IS NULL) AS gn,
#state := state AS sn,
s.id, s.date, s.state
FROM (
SELECT #r := 0,
#state := NULL
) vars,
t_range s
ORDER BY
date, state
) q
GROUP BY gn
More details at : https://explainextended.com/2009/07/24/mysql-grouping-continuous-ranges/
Hopefully the title makes any sense.
For this example I'll have the next table in my database
measurements
==================================
stn | date | temp | time =
1 | 01-12-2001 | 2.0 | 14:30 =
1 | 01-12-2001 | 2.1 | 14:31 =
1 | 03-12-2001 | 1.9 | 21:34 =
2 | 01-12-2001 | 4.5 | 12:48 =
2 | 01-12-2001 | 4.7 | 12:49 =
2 | 03-12-2001 | 4.9 | 11:01 =
==================================
And so on and so forth.
Each station (stn) has many measurements, one per day second. Now I want to select the temp of each station of the last 30 days measurements where the station has at least 30 temperature measurements.
I was playing with subquerys and group by, but I can't seem to figure it out.
Hope someone can help me out here.
edited the table
My example was oversimplified leaving a critical piece of information out. Please review the question.
select t1.stn,t1.date,t1.temp,t1.rn from (
select *,
#num := if(#stn = stn, #num + 1, 1) as rn,
#stn := stn as id_stn
from table,(select #stn := 0, #num := 1) as r
order by stn asc, date desc) as t1
inner join (select `stn`
from table
where concat_ws(' ',date,time) >= now() - interval 30 day
group by `stn`
having count(*) >= 30) as t
on t1.stn = t.stn
and t1.rn <= 30
order by stn,date desc,time desc
This is the query that should select Last 30 entries where there are at least 30 entries for a station
This query is based on the answer here by nick rulez, so please upvote him
SELECT t1.stn, t1.date, t1.temp, t1.time FROM
(
SELECT *,
#num := if(#stn = stn, #num + 1, 1) as rn,
#stn := stn as id_stn
FROM
`tablename`,
(SELECT #stn := 0, #num := 1) as r
ORDER BY stn asc, date desc
) as t1
INNER JOIN
(
SELECT `stn`
FROM `tablename`
GROUP BY `stn`
HAVING COUNT(*) >= 30
) as t
ON t1.stn = t.stn
AND t1.rn <= 30
ORDER BY stn, date desc, time desc
I have tested it on a sample database I made based on your schema and is working fine.
To know more about such queries have a look here Within-group quotas (Top N per group)
SELECT stn, date, temp FROM
(
SELECT stn, date, temp, #a:=IF(#lastStn=stn, #a+1, 1) countPerStn, #lastStn:=stn
FROM cache
GROUP BY stn, date
ORDER BY stn, date DESC
) as tempTable
WHERE countPerStn > 30;
Is the query I was looking for, sorry if my question was 'so wrong' that it pushed you all in the wrong direction. I'll up vote the answers who'm helped me to find the needed query.