仅选择一行具有一对多关系表的最大字段

Question

我有2个表，Chapter表有很多行，其中manga_id是id Manga表

漫画表

ID | NAME      | SLUG 
1    One Piece   one-piece
2    Naruto      naruto
3    Gintama     gintama

章节表

MANGA_ID | NAME    | SLUG             | CREATED_AT
1          Chap 1    One-Piece-Chap-1   2016/01/01
1          Chap 2    One-Piece-Chap-2   2016/01/02
1          Chap 3    One-Piece-Chap-3   2016/01/03
2          Chap 1    Naruto-Chap-1      2016/01/02
2          Chap 2    Naruto-Chap-2      2016/01/03
2          Chap 3    Naruto-Chap-3      2016/01/04
3          Chap 1    Gintama-Chap-1     2016/01/07
3          Chap 4    Gintama-Chap-4     2016/01/09

我正在寻找只有1个漫画有1个章节，按created_at DESC

排序

我寻找的示例表：

Manga_ID | Manga_NAME | NAME    | SLUG             | CREATED_AT
3          Gintama      Chap 4    Gintama-Chap-4     2016/01/09
2          Naruto       Chap 3    Naruto-Chap-3      2016/01/04
1          One Piece    Chap 3    One-Piece-Chap-3   2016/01/03

我非常感谢任何人回答这个主题并节省我的一天

Answer 1

SELECT t1.MANGA_ID, t2.NAME AS Manga_NAME,t1.NAME,t1.slug,t1.CREATED_AT
FROM Chapter t1
INNER JOIN Manga t2 ON t1.MANGA_ID = t2.ID
WHERE t1.CREATED_AT = (SELECT MAX(CREATED_AT) from Chapter t3 where t3.MANGA_ID = t1.MANGA_ID)

Answer 2

SELECT mt.id as MANGA_ID, mt.NAME as MANGA_NAME, ct.NAME, ct.SLUG, MAX(ct.CREATED_AT) as CREATED_AT FROM Chapter ct LEFT JOIN Manga mt ON (mt.id = ct.MANGA_ID) GROUP BY ct.MANGA_ID

这应该可以解决问题。