不,Oracle
不会将嵌套在一个以上深度的子查询关联起来(也不是MysqL
)。
这是一个众所周知的问题。
用这个:
SELECT p.post_id, c.*
FROM posts
JOIN (
SELECT c.*, ROW_NUMBER() OVER (PARTITION BY post_id ORDER BY created_date ASC) AS rn
FROM comments c
) c
ON c.post_id = p.post_id
AND rn = 1