Postgres ORDER BY DESC 然后 ASC [重复]

Question

我有一个递归查询

With RECURSIVE tree AS
 (
 SELECT * FROM comments WHERE id = 83
 UNION
 SELECT t.*
      From comments t
 JOIN tree rt ON rt.parent_id = t.id

 )
 SELECT * from tree ORDER BY id DESC LIMIT 5

如何通过 ASC 再订购一次？

Edit1: 尝试了这个解决方案： Get the last N rows in the database in order?

With RECURSIVE tree AS
 (
 SELECT * FROM comments WHERE id = 83
 UNION
 SELECT t.*
      From comments t
 JOIN tree rt ON rt.parent_id = t.id

 )
 select * from (SELECT * from tree ORDER BY id DESC LIMIT 5) order by id 

给我一​​个错误：

ERROR:  subquery in FROM must have an alias 

Answer 1

在 PostgreSQL 中，所有表表达式（FROM 之后的选择）都需要命名。也就是说，他们需要有一个别名。只需添加任何别名。比如我加了x，如：

With RECURSIVE tree AS
 (
 SELECT * FROM comments WHERE id = 83
 UNION
 SELECT t.*
      From comments t
 JOIN tree rt ON rt.parent_id = t.id

 )
 select * from (SELECT * from tree ORDER BY id DESC LIMIT 5) x order by id 

你发现了吗？

Answer 2

select * from (SELECT * from tree ORDER BY comment_id DESC LIMIT 5) t order by comment_id