LeetCode（数据库）- 联赛信息统计

Posted 2021-12-25 程序员牧码

题目链接：点击打开链接

题目大意：略。

解题思路：略。

AC 代码

-- 解决方案(1)
SELECT distinct team_name, 
    COUNT(*) AS matches_played,
    SUM(
        CASE 
        WHEN (team_id=home_team_id AND home_team_goals>away_team_goals) OR
             (team_id=away_team_id AND home_team_goals<away_team_goals) THEN 3
        WHEN (team_id=home_team_id AND home_team_goals<away_team_goals) OR 
             (team_id=away_team_id AND home_team_goals>away_team_goals) THEN 0 
        ELSE 1 END) AS points, 
    SUM(IF(team_id=home_team_id,home_team_goals,away_team_goals)) AS goal_for,
    SUM(IF(team_id=home_team_id,away_team_goals,home_team_goals)) AS goal_against,
    SUM(IF(team_id=home_team_id,home_team_goals,away_team_goals)) - SUM(IF(team_id=home_team_id,away_team_goals,home_team_goals)) AS goal_diff
FROM Teams JOIN Matches ON team_id=home_team_id OR team_id=away_team_id
GROUP BY team_id
ORDER BY points DESC, goal_diff DESC, team_name ASC

-- 解决方案(2)
WITH t1 AS(SELECT team_id, COUNT(*) matches_played
FROM (SELECT home_team_id team_id FROM Matches
UNION ALL
SELECT away_team_id FROM Matches) t
GROUP BY team_id),

t_point AS(SELECT home_team_id, away_team_id, 
SUM(IF(home_team_goals > away_team_goals, 3, IF(home_team_goals = away_team_goals, 1, 0))) home_points,
SUM(IF(home_team_goals > away_team_goals, 0, IF(home_team_goals = away_team_goals, 1, 3))) away_points
FROM Matches
GROUP BY home_team_id, away_team_id),

t2 AS(SELECT team_id, SUM(points) points
FROM (SELECT home_team_id team_id, home_points points FROM t_point
UNION ALL
SELECT away_team_id, away_points FROM t_point) t
GROUP BY team_id),

t3 AS(SELECT team_id, SUM(goal_for) goal_for, SUM(goal_against) goal_against, SUM(goal_for) - SUM(goal_against) goal_diff
FROM (SELECT home_team_id team_id, SUM(home_team_goals) goal_for, SUM(away_team_goals) goal_against
FROM Matches
GROUP BY home_team_id
UNION ALL
SELECT away_team_id team_id, SUM(away_team_goals) goal_for, SUM(home_team_goals) goal_against
FROM Matches
GROUP BY away_team_id) t
GROUP BY team_id)

SELECT team_name, matches_played, points, goal_for, goal_against, goal_diff
FROM Teams JOIN t1 USING(team_id) JOIN t2 USING(team_id) JOIN t3 USING(team_id)
ORDER BY points DESC, goal_diff DESC, team_name