子查询未返回预期结果

Question

我正在尝试获取season.id的最大日期的match。 查询是这样的：

SELECT s.id AS season_id,
s.name AS season_name,
s.competition_id AS competition_id
FROM competition_seasons s
INNER JOIN competition_rounds r ON r.season_id = s.id
INNER JOIN `match` m ON m.round_id = r.id
WHERE s.competition_id = 89
AND m.datetime = (SELECT MAX(m.datetime) FROM `match` m WHERE m.round_id = r.id)
GROUP BY s.id

如您所见，我有一个名为competition_seasons的表，其中包含可用于比赛的所有季节，在此表上，我可以获得比赛的所有信息，在这种情况下，比赛的ID为{{1 }}。 后来我通过表89获得了本赛季所有可用的rounds，在competition_rounds上玩了match，所以我使用round在INNER JOIN上，因为我只需要获取具有match的{​​{1}}。

比赛rounds的回合不同，季节不同，例如：

• 2017/2018
• 2016/2017
• 2015/2016

查询应该返回matches，因为最后一个赛季的89和2017/2018字段说明比赛进行时，match在比赛中进行季节MAX(m.datetime)表示日期可以从2017年开始，到2018年结束（因此，在该季节的两年内）。

查询的结果改为2011，这绝对没有意义。

我在查询中做错了什么？

competition_seasons

match

competition_rounds

2017/2018

匹配

| id | name       | competition_id
 1     2017/2018       89
 2     2016/2017       89
 3     2015/2016       89

预期结果：season_id = 1，因为此季节的| id | name | season_id 1 First 1 2 Second 1 3 First 2 4 Second 2 5 First 3 的字段|id | datetime | round_id 1 2018-03-08 00:00:0 1 2 2017-09-10 20:30:0 1 3 2017-04-18 15:30:0 3 4 2016-03-08 00:00:0 3 5 2015-04-08 00:00:0 4 6 2015-05-08 00:00:0 5 比上一个季节大。

Answer 1

我认为ORDER BY和LIMIT可以工作：

SELECT s.id AS season_id, s.name AS season_name,
       s.competition_id AS competition_id
FROM competition_seasons s INNER JOIN
     competition_rounds r
     ON r.season_id = s.id INNER JOIN 
     `match` m
     ON m.round_id = r.id
WHERE s.competition_id = 89
ORDER BY m.datetime DESC
LIMIT 1;

Answer 2

尝试一下：

SELECT s.id AS season_id,
s.name AS season_name,
s.competition_id AS competition_id
FROM competition_seasons s
INNER JOIN competition_rounds r ON r.season_id = s.id
INNER JOIN `match` m ON m.round_id = r.id
WHERE s.competition_id = 89
AND m.datetime = (SELECT MAX(m1.datetime) FROM `match` m1
                  INNER JOIN competition_rounds r1 
                  ON m1.round_id = r1.id
                  INNER JOIN competition_seasons s1
                  ON r1.season_id = s1.id
                  AND s1.competition_id = 89)