MYSQL query winning streak including score - mysql

Question

I have a query-generated table that counts up the winning streak as long as the player keeps winning. When they player gets a positive score, the streak rises with 1, if he gets a negative score, the streak falls back to 0. The table looks like this:
+--------+------------------+--------+--------+
| player | timestamp | points | streak |
+--------+------------------+--------+--------+
| John | 22/11/2012 23:01 | -2 | 0 |
| John | 22/11/2012 23:02 | 3 | 1 |
| John | 22/11/2012 23:04 | 5 | 2 |
| John | 22/11/2012 23:05 | -2 | 0 |
| John | 22/11/2012 23:18 | 15 | 1 |
| John | 23/11/2012 23:20 | 5 | 2 |
| Chris | 27/11/2012 22:12 | 20 | 1 |
| Chris | 27/11/2012 22:14 | -12 | 0 |
| Chris | 27/11/2012 22:17 | 4 | 1 |
| Chris | 27/11/2012 22:18 | -4 | 0 |
| Chris | 27/11/2012 22:20 | 10 | 1 |
| Chris | 27/11/2012 22:21 | 20 | 2 |
| Chris | 27/11/2012 22:22 | 90 | 3 |
+--------+------------------+--------+--------+
I would like to get the players maximum streak, which is easy to get ofcourse, but I would also like to include the points that the player scored in that particular streak. So, for the above example the result would have to look like this:
+--------+--------+-----------+
| player | points | maxstreak |
+--------+--------+-----------+
| John | 20 | 2 |
| Chris | 120 | 3 |
+--------+--------+-----------+
Any idea's of how I could achieve this? Thanks in advance!

Answer 1

I have not had a chance to actually try this, but is SHOULD work using mySQL Variables...
At the beginning, the inner-most query just queries from your scores table and forces the data in order of player and timestamp. From that, I have to process sequentially with MySQL variables. First thing... on each new record being processed, if I am on a different "Player" (which should ACTUALLY be based on an ID instead of name), I am resetting the streak, points, maxStreak, maxStreakPoints to zero, THEN setting the last user to whoever its about to process.
Immediately after that, I am checking for the streak status, points, etc...
Once all have been tabulated, I then use the OUTERMOST query to get on a per-player basis, what their highest max streak / max streak points.
SELECT
Final.Player,
MAX( Final.MaxStreak ) MaxStreak,
MAX( Final.MaxStreakPoints ) MaxStreakPoints
FROM
(
SELECT
PreOrd.Player,
PreOrd.TimeStamp,
PreOrd.Points,
#nStreak := case when PreOrd.Points < 0 then 0
when PreOrd.Player = #cLastPlayer then #nStreak +1
else 1 end Streak,
#nStreakPoints := case when #nStreak = 1 then PreOrd.Points
when #nStreak > 1 then #nStreakPoints + PreOrd.Points
else 0 end StreakPoints,
#nMaxStreak := case when PreOrd.Player != #cLastPlayer then #nStreak
when #nStreak > #nMaxStreak then #nStreak
else #nMaxStreak end MaxStreak,
#nMaxStreakPoints := case when PreOrd.Player != #cLastPlayer then #nStreakPoints
when #nStreak >= #nMaxStreak and #nStreakPoints > #nMaxStreakPoints then #nStreakPoints
else #nMaxStreakPoints end MaxStreakPoints,
#cLastPlayer := PreOrd.Player PlayerChange
FROM
( select
S.Player,
S.TimeStamp,
S.Points
from
Scores2 S
ORDER BY
S.Player,
S.TimeStamp,
S.`index` ) PreOrd,
( select
#nStreak := 0,
#nStreakPoints := 0,
#nMaxStreak := 0,
#nMaxStreakPoints := 0,
#cLastPlayer := '~' ) SQLVars
) as Final
group by
Final.Player
Now, this could give a false max streak points, such that on a single score the person has 90 points, then a streak of 1 for 10 points, 2 for 10 points, 3 for 10 points, 30 total.. Still thinking on that though... :)
Here's what I get when I add the index column as you've made available from data supplied
SQL Fiddle Showing my solution...

Answer 2

My recommendation is to store additional information when you calculate the streak. For instance, you could store the time stamp when the streak began.
A less-serious recommendation is to switch to another database, that supports window functions. This would be much easier.
The approach is to find when the streak began and then sum up everything between that time and the max streak. To do this, we'll use a correlated subquery:
select t.*,
(select max(timestamp) from t t2 where t2.timestamp <= t.timestamp and t2.player = t.player and t2.streak = 0
) as StreakStartTimeStamp
from t
where t.timeStamp = (select max(streak) from t t2 where t.player = t2.player)
Now, we will embed this query as a subquery, so we can add the appropriate times:
select t.player,
sum(s.points)
from t join
(select t.*,
(select max(timestamp) from t t2 where t2.timestamp <= t.timestamp and t2.player = t.player and t2.streak = 0
) as StreakStartTimeStamp
from t
where t.streak = (select max(streak) from t t2 where t.player = t2.player)
) s
on t.player = s.player
group by t.player
I haven't tested this query, so there are probably some syntax errors. However, the approach should work. You may want to have indexes on the table, on streak and timestamp for performance reasons.