mysql - 独特的一栏

Question

你好，

我有两个表:

episodes:

• id
• episode
• season
• series
• title

series:

• id
• name

我想收到最后添加的剧集(不重复系列)

例如: 我在《行尸走肉》中添加了两集，在《House M.D》中添加了一集。

所以，结果应该是:

Episode 2 - Walking Dead

Episode 1 - House M.D.

此时我的查询是:

SELECT *, e.id AS episodeId, s.id AS seriesId 
FROM episodes AS e 
LEFT JOIN series AS s ON e.series = s.id 
ORDER BY e.id DESC LIMIT 25

Answer 1

尝试使用 MAX(e.id)

SELECT MAX(e.id) AS episodeId, s.id AS seriesId 
FROM episodes AS e 
LEFT JOIN series AS s ON e.series = s.id 
GROUP BY s.id

如果您需要更多列，请使用联接

SELECT * 
FROM episodes AS ep
JOIN
(SELECT MAX(e.id) AS episodeId, s.id AS seriesId 
FROM episodes AS e 
LEFT JOIN series AS s ON e.series = s.id 
GROUP BY s.id) temp
ON temp.episodeId =ep.id