Leetcode力扣 MySQL数据库 1841 联赛信息统计
1841 联赛信息统计
SQL架构
Create table If Not Exists Teams_1841 (team_id int, team_name varchar(20));
Create table If Not Exists Matches_1841 (home_team_id int, away_team_id int, home_team_goals int, away_team_goals int);
Truncate table Teams_1841;
insert into Teams_1841 (team_id, team_name) values ('1', 'Ajax');
insert into Teams_1841 (team_id, team_name) values ('4', 'Dortmund');
insert into Teams_1841 (team_id, team_name) values ('6', 'Arsenal');
Truncate table Matches_1841;
insert into Matches_1841 (home_team_id, away_team_id, home_team_goals, away_team_goals) values ('1', '4', '0', '1');
insert into Matches_1841 (home_team_id, away_team_id, home_team_goals, away_team_goals) values ('1', '6', '3', '3');
insert into Matches_1841 (home_team_id, away_team_id, home_team_goals, away_team_goals) values ('4', '1', '5', '2');
insert into Matches_1841 (home_team_id, away_team_id, home_team_goals, away_team_goals) values ('6', '1', '0', '0');
Table: Teams
+----------------+---------+
| Column Name | Type |
+----------------+---------+
| team_id | int |
| team_name | varchar |
+----------------+---------+
team_id 是该表主键.
每一行都包含了一个参加联赛的队伍信息.
Table: Matches
+-----------------+---------+
| Column Name | Type |
+-----------------+---------+
| home_team_id | int |
| away_team_id | int |
| home_team_goals | int |
| away_team_goals | int |
+-----------------+---------+
(home_team_id, away_team_id) 是该表主键.
每一行包含了一次比赛信息.
home_team_goals 代表主场队得球数.
away_team_goals 代表客场队得球数.
获得球数较多的队伍为胜者队伍.
写一段SQL，用来报告联赛信息. 统计数据应使用已进行的比赛来构建，其中获胜球队获得三分，而失败球队获得零分. 如果打平，两支球队都得一分.
result表的每行应包含以下信息:
team_name - Teams表中的队伍名字
matches_played - 主场与客场球队进行的比赛次数.
points - 球队获得的总分数.
goal_for - 球队在所有比赛中获取的总进球数
goal_against - 球队在所有比赛中，他的对手球队的所有进球数
goal_diff - goal_for - goal_against.
按分数降序返回结果表。 如果两队或多队得分相同，则按goal_diff 降序排列。 如果仍然存在平局，则以 team_name 按字典顺序排列它们。
查询的结果格式如下例所示:
Teams table:
+---------+-----------+
| team_id | team_name |
+---------+-----------+
| 1 | Ajax |
| 4 | Dortmund |
| 6 | Arsenal |
+---------+-----------+
Matches table:
+--------------+--------------+-----------------+-----------------+
| home_team_id | away_team_id | home_team_goals | away_team_goals |
+--------------+--------------+-----------------+-----------------+
| 1 | 4 | 0 | 1 |
| 1 | 6 | 3 | 3 |
| 4 | 1 | 5 | 2 |
| 6 | 1 | 0 | 0 |
+--------------+--------------+-----------------+-----------------+
Result table:
+-----------+----------------+--------+----------+--------------+-----------+
| team_name | matches_played | points | goal_for | goal_against | goal_diff |
+-----------+----------------+--------+----------+--------------+-----------+
| Dortmund | 2 | 6 | 6 | 2 | 4 |
| Arsenal | 2 | 2 | 3 | 3 | 0 |
| Ajax | 4 | 2 | 5 | 9 | -4 |
+-----------+----------------+--------+----------+--------------+-----------+
Ajax (team_id=1) 有4场比赛: 2败2平. 总分数 = 0 + 0 + 1 + 1 = 2.
Dortmund (team_id=4) 有2场比赛: 2胜. 总分数 = 3 + 3 = 6.
Arsenal (team_id=6) 有2场比赛: 2平. 总分数 = 1 + 1 = 2.
Dortmund 是积分榜上的第一支球队. Ajax和Arsenal 有同样的分数, 但Arsenal的goal_diff高于Ajax, 所以Arsenal在表中的顺序在Ajaxzhiqian.
解题
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_goalsaway_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_1841 JOIN Matches_1841 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;