Question

我试图使用MySQL计算一些关于运动员的统计数据。该数据库有3个表。

相关的Rextester：http://rextester.com/SNAL27886

播放器

球员名单。

+----+---------+-----------+
| id | team_id | lastname  |
+----+---------+-----------+
|  1 |       1 | Moubandje |
|  2 |       2 | Rüfli     |
|  3 |       3 | Selnaes   |
|  4 |       1 | Somália   |
|  5 |       4 | Kerbrat   |
+----+---------+-----------+

匹配

团队名单。

+----+--------------+--------------+-----+
| id | home_team_id | away_team_id | day |
+----+--------------+--------------+-----+
|  1 |            1 |            2 |   1 |
|  2 |            2 |            1 |   2 |
|  3 |            2 |            3 |   3 |
|  4 |            3 |            4 |   4 |
|  5 |            3 |            5 |   5 |
+----+--------------+--------------+-----+

player_match

每场比赛的球员统计数据。

+-----------+----------+-----------+------------+-------+
| player_id | match_id | rating    | substitute | goals |
+-----------+----------+-----------+------------+-------+
|         1 |        1 |         6 |          0 |     2 |
|         2 |        2 |         5 |          1 |     0 |
|         1 |       10 |         3 |          0 |     0 |
+-----------+----------+---------+-----------+----------+

以下是我查询有关玩家的各种统计数据的查询（例如他的目标数量，或者他的全球平均评分）：

SELECT
  p.id AS p_id,
  p.lastname AS lastname,
  p.team_id as team_id,
  AVG(pm.rating) AS avg_rating,
  COUNT(pm.player_id) AS nb_matches,
  SUM(pm.substitute) AS nb_matches_substitute,
  SUM(pm.goals) AS goals,
  (SUM(pm.goals) / COUNT(pm.player_id)) AS goals_per_matches
FROM
  player p
  INNER JOIN player_match pm ON pm.player_id = p.id
  INNER JOIN `match` m ON pm.match_id = m.id AND (m.home_team_id = p.team_id OR m.away_team_id = p.team_id)
GROUP BY
  p.id,
  p.lastname,
  p.team_id
ORDER BY
  avg_rating DESC, lastname ASC
;

我还想计算他的球队的最后5场比赛的球员的平均评分（如果球员没有参加比赛，他的评分必须为0）。然后，我想通过这个特定的平均评级来排序列表的结果。

以下是我的查询，以检索其团队最近5场比赛的特定球员的平均评分以及每场比赛的评分为字符串：

SELECT
  SUM(pm1.rating) / COUNT(m1.id) last_5_matches_rating,
  GROUP_CONCAT(CONCAT(m1.day, '=', COALESCE(pm1.rating, '~')) ORDER BY m1.day)
FROM
  `match` m1
  INNER JOIN (
    SELECT m2.id, m2.home_team_id, m2.away_team_id
    FROM `match` m2
    AND (m2.home_team_id=1 OR m2.away_team_id=1)
    ORDER BY m2.day DESC
    LIMIT 5
  ) last_5_games ON m1.id = last_5_games.id
  LEFT JOIN player_match pm1 ON m1.id = pm1.match_id AND pm1.player_id=4

这是队员＃1中队员＃4成员的结果。

有没有办法将上一个查询作为前一个查询的子查询执行，并按last_5_matches_rating订购结果？

我期望的是以下列的结果：

| id | lastname | team_id | avg_rating | last_5_matches_rating | nb_matches | ...

Answer 1

我仍然无法获得返回预期结果的查询，但我已经转而采用另一种明显的方式来完成这项工作。

我在播放器表格中添加了两个计算列：last_five_matches_avg_rating和last_five_matches_ratings。

每次更新数据库后，都会执行一个脚本：它遍历所有玩家，执行第二个查询以检索统计数据并将这些计算出的统计数据存储在相应的列中。

这是这个PHP脚本（它使用Doctrine ORM）：

<?php

namespace App;

use App\Entity\Player;
use Doctrine\Common\Persistence\ManagerRegistry;

class StatsComputer
{
    private $doctrine;

    public function __construct(ManagerRegistry $doctrine)
    {
        $this->doctrine = $doctrine;
    }

    public function update()
    {
        $manager = $this->doctrine->getManager();
        $stmt = $manager->getConnection()->prepare(<<<SQL
SELECT
  SUM(pm1.rating) / COUNT(m1.id) last_5_matches_avg_rating,
  GROUP_CONCAT(COALESCE(pm1.rating, '0')) ORDER BY m1.day) last_5_matches_ratings
FROM
  `match` m1
  INNER JOIN (
    SELECT m2.id, m2.home_team_id, m2.away_team_id
    FROM `match` m2
    AND (m2.home_team_id=:team_id OR m2.away_team_id=:team_id)
    ORDER BY m2.day DESC
    LIMIT 5
  ) last_5_games ON m1.id = last_5_games.id
  LEFT JOIN player_match pm1 ON m1.id = pm1.match_id AND pm1.player_id=:player_id
SQL
);

        foreach ($this->doctrine->getRepository(Player::class)->findAll() as $player) {
            /**
             * @var $player Player
             */
            $stmt->execute(['team_id' => $player->team->id, 'player_id' => $player->id]);
            $results = $stmt->fetch();

            $player->last5MatchesAvgRating = $results['last_5_matches_avg_rating'];
            $player->last5MatchesRatings = array_map('intval', explode(',', $results['last_5_matches_ratings']));
        }

        $manager->flush();
    }
}

第一个查询的更新版本：

SELECT
  p.id AS p_id,
  p.lastname AS lastname,
  p.team_id as team_id,
  p.last_5_matches_avg_rating as last_5_matches_avg_rating,
  p.last_5_matches_ratings as last_5_matches_ratings,
  AVG(pm.rating) AS avg_rating,
  COUNT(pm.player_id) AS nb_matches,
  SUM(pm.substitute) AS nb_matches_substitute,
  SUM(pm.goals) AS goals,
  (SUM(pm.goals) / COUNT(pm.player_id)) AS goals_per_matches
FROM
  player p
  INNER JOIN player_match pm ON pm.player_id = p.id
  INNER JOIN `match` m ON pm.match_id = m.id AND (m.home_team_id = p.team_id OR m.away_team_id = p.team_id)
GROUP BY
  p.id,
  p.lastname,
  p.team_id,
  p.last_5_matches_avg_rating,
  p.last_5_matches_ratings
ORDER BY
  last_5_matches_avg_rating DESC, avg_rating DESC, lastname ASC
;

这不是我最初想要的，但它确实有效（这个数据库的更新次数很少）并且速度很快。

我希望它可以帮助别人。

使用MySQL为每个返回的行执行相关子查询

1 个答案: