longest winning streak by query

Question

I have a table like below:

id     homeTeam    awayTeam   homeScore    awayScore
1         t1          t2          3            2
2         t3          t7          0            1
.          .           .          .            .
.          .           .          .            .
.          .           .          .            .

which is a Soccer match results from a loocal league. I wanna get "longest win streak", "longest lose streak" and ........ with just a query. I looked around and found the oracle version, but I couldn't find out how to do this? PS: I have mysql database. thanks in advance

Answer 1

Here's one way, but I've got a feeling you're not going to like it...

Consider the following data DDL's...

CREATE TABLE results
(id     INT NOT NULL AUTO_INCREMENT PRIMARY KEY
,homeTeam    INT NOT NULL
,awayTeam    INT NOT NULL
,homeScore    INT NOT NULL
,awayScore INT NOT NULL
);

INSERT INTO results VALUES
(1,1,2,3,2),
(2,3,4,0,1),
(3,2,1,2,0),
(4,4,3,1,0),
(5,3,2,1,2),
(6,2,3,0,2),
(7,1,4,4,1),
(8,4,1,1,2),
(9,1,3,3,0),
(10,3,1,1,0),
(11,4,2,1,0),
(12,2,4,1,2);

From here, we can obtain an intermediate result as follows...

SELECT x.*, COUNT(*) rank
  FROM
     ( SELECT id,hometeam team, CASE WHEN homescore > awayscore THEN 'w' ELSE 'l' END result FROM results 
       UNION
       SELECT id,awayteam, CASE WHEN awayscore > homescore THEN 'w' ELSE 'l' END result FROM results
     ) x
  JOIN 
     ( SELECT id,hometeam team, CASE WHEN homescore > awayscore THEN 'w' ELSE 'l' END result FROM results 
       UNION
       SELECT id,awayteam, CASE WHEN awayscore > homescore THEN 'w' ELSE 'l' END result FROM results
     ) y
    ON y.team = x.team
   AND y.id <= x.id
 GROUP
    BY x.id
     , x.team
 ORDER
    BY team, rank;

+----+------+--------+------+
| id | team | result | rank |
+----+------+--------+------+
|  1 |    1 | w      |    1 |
|  3 |    1 | l      |    2 |
|  7 |    1 | w      |    3 |
|  8 |    1 | w      |    4 |
|  9 |    1 | w      |    5 |
| 10 |    1 | l      |    6 |
|  1 |    2 | l      |    1 |
|  3 |    2 | w      |    2 |
|  5 |    2 | w      |    3 |
|  6 |    2 | l      |    4 |
| 11 |    2 | l      |    5 |
| 12 |    2 | l      |    6 |
|  2 |    3 | l      |    1 |
|  4 |    3 | l      |    2 |
|  5 |    3 | l      |    3 |
|  6 |    3 | w      |    4 |
|  9 |    3 | l      |    5 |
| 10 |    3 | w      |    6 |
|  2 |    4 | w      |    1 |
|  4 |    4 | w      |    2 |
|  7 |    4 | l      |    3 |
|  8 |    4 | l      |    4 |
| 11 |    4 | w      |    5 |
| 12 |    4 | w      |    6 |
+----+------+--------+------+

By inspection, we can see that team 1 has the longest winning streak (3 consecutive 'w's). You can set up a couple of @vars to track this or, if you're slightly masochistic (like me) you can do something slower, longer, and more complicated...

SELECT a.team
     , MIN(c.rank) - a.rank + 1 streak
  FROM (SELECT x.*, COUNT(*) rank
  FROM
     ( SELECT id,hometeam team, CASE WHEN homescore > awayscore THEN 'w' ELSE 'l' END result FROM results 
       UNION
       SELECT id,awayteam, CASE WHEN awayscore > homescore THEN 'w' ELSE 'l' END result FROM results
     ) x
  JOIN 
     ( SELECT id,hometeam team, CASE WHEN homescore > awayscore THEN 'w' ELSE 'l' END result FROM results 
       UNION
       SELECT id,awayteam, CASE WHEN awayscore > homescore THEN 'w' ELSE 'l' END result FROM results
     ) y
    ON y.team = x.team
   AND y.id <= x.id
 GROUP
    BY x.id
     , x.team
     ) a
  LEFT 
  JOIN (SELECT x.*, COUNT(*) rank
  FROM
     ( SELECT id,hometeam team, CASE WHEN homescore > awayscore THEN 'w' ELSE 'l' END result FROM results 
       UNION
       SELECT id,awayteam, CASE WHEN awayscore > homescore THEN 'w' ELSE 'l' END result FROM results
     ) x
  JOIN 
     ( SELECT id,hometeam team, CASE WHEN homescore > awayscore THEN 'w' ELSE 'l' END result FROM results 
       UNION
       SELECT id,awayteam, CASE WHEN awayscore > homescore THEN 'w' ELSE 'l' END result FROM results
     ) y
    ON y.team = x.team
   AND y.id <= x.id
 GROUP
    BY x.id
     , x.team
     ) b 
    ON b.team = a.team
   AND b.rank = a.rank - 1 
   AND b.result = a.result
  LEFT 
  JOIN (SELECT x.*, COUNT(*) rank
  FROM
     ( SELECT id,hometeam team, CASE WHEN homescore > awayscore THEN 'w' ELSE 'l' END result FROM results 
       UNION
       SELECT id,awayteam, CASE WHEN awayscore > homescore THEN 'w' ELSE 'l' END result FROM results
     ) x
  JOIN 
     ( SELECT id,hometeam team, CASE WHEN homescore > awayscore THEN 'w' ELSE 'l' END result FROM results 
       UNION
       SELECT id,awayteam, CASE WHEN awayscore > homescore THEN 'w' ELSE 'l' END result FROM results
     ) y
    ON y.team = x.team
   AND y.id <= x.id
 GROUP
    BY x.id
     , x.team
     ) c 
    ON c.team = a.team
   AND c.rank >= a.rank 
   AND c.result = a.result
  LEFT 
  JOIN (SELECT x.*, COUNT(*) rank
  FROM
     ( SELECT id,hometeam team, CASE WHEN homescore > awayscore THEN 'w' ELSE 'l' END result FROM results 
       UNION
       SELECT id,awayteam, CASE WHEN awayscore > homescore THEN 'w' ELSE 'l' END result FROM results
     ) x
  JOIN 
     ( SELECT id,hometeam team, CASE WHEN homescore > awayscore THEN 'w' ELSE 'l' END result FROM results 
       UNION
       SELECT id,awayteam, CASE WHEN awayscore > homescore THEN 'w' ELSE 'l' END result FROM results
     ) y
    ON y.team = x.team
   AND y.id <= x.id
 GROUP
    BY x.id
     , x.team
     ) d 
    ON d.team = a.team
   AND d.rank = c.rank + 1 
   AND d.result = a.result
 WHERE a.result = 'w'
   AND b.id IS NULL
   AND c.id IS NOT NULL
   AND d.id IS NULL
 GROUP 
    BY a.team
     , a.rank
 ORDER 
    BY streak DESC 
 LIMIT 1; 

 +------+--------+
 | team | streak |
 +------+--------+
 |    1 |      3 |
 +------+--------+

Note that this doesn't account for individual match ties (a modest change to the repeated subquery), nor if two teams have longest winning streaks of equal length (requiring a JOIN of everything here back on itself!).