我在PostgreSQL 8.3中有一个简单的SQL查询,它抓取了一堆注释。我在WHERE子句中为IN构造提供了一个排序的值列表:

SELECT * FROM comments WHERE (comments.id IN (1,3,2,4));

这将以任意顺序返回注释,在my中恰好是id,如1,2,3,4。

我希望结果行像in结构中的列表一样排序:(1,3,2,4)。 如何实现这一目标?


当前回答

让我们对已经说过的内容有一个直观的印象。例如,你有一个带有一些任务的表:

SELECT a.id,a.status,a.description FROM minicloud_tasks as a ORDER BY random();

 id |   status   |   description    
----+------------+------------------
  4 | processing | work on postgres
  6 | deleted    | need some rest
  3 | pending    | garden party
  5 | completed  | work on html

并且您希望按状态对任务列表进行排序。 status是一个字符串值列表:

(processing, pending,  completed, deleted)

诀窍是给每个状态值一个整数,并以数字顺序排列列表:

SELECT a.id,a.status,a.description FROM minicloud_tasks AS a
  JOIN (
    VALUES ('processing', 1), ('pending', 2), ('completed', 3), ('deleted', 4)
  ) AS b (status, id) ON (a.status = b.status)
  ORDER BY b.id ASC;

这就导致:

 id |   status   |   description    
----+------------+------------------
  4 | processing | work on postgres
  3 | pending    | garden party
  5 | completed  | work on html
  6 | deleted    | need some rest

信贷@user80168

其他回答

这里有另一个解决方案,它使用了一个常量表(http://www.postgresql.org/docs/8.3/interactive/sql-values.html):)

SELECT * FROM comments AS c,
(VALUES (1,1),(3,2),(2,3),(4,4) ) AS t (ord_id,ord)
WHERE (c.id IN (1,3,2,4)) AND (c.id = t.ord_id)
ORDER BY ord

但我不确定这是表现性的。

我现在有一堆答案了。我可以得到一些投票和评论,这样我就知道哪一个是赢家!

谢谢大家:-)

在Postgresql:

select *
from comments
where id in (1,3,2,4)
order by position(id::text in '1,3,2,4')

你可以很容易地使用(在PostgreSQL 8.2中引入)VALUES(),()。

语法是这样的:

select c.*
from comments c
join (
  values
    (1,1),
    (3,2),
    (2,3),
    (4,4)
) as x (id, ordering) on c.id = x.id
order by x.ordering

无序列,只适用于8.4:

select * from comments c
join 
(
    select id, row_number() over() as id_sorter  
    from (select unnest(ARRAY[1,3,2,4]) as id) as y
) x on x.id = c.id
order by x.id_sorter
select * from comments where comments.id in 
(select unnest(ids) from bbs where id=19795) 
order by array_position((select ids from bbs where id=19795),comments.id)

这里,[bbs]是主表,它有一个名为ids的字段, id是存储注释的数组。id。

在postgresql 9.6中通过