sql - 按 IN 值列表排序

Question

我在 PostgreSQL 8.3 中有一个简单的 SQL 查询，它获取了一堆注释。我为子句中的构造提供了一个排序的值列表：INWHERE

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

这会以任意顺序返回评论，在我看来，这些评论恰好是1,2,3,4.

我希望生成的行像IN构造中的列表一样排序：(1,3,2,4)。
如何做到这一点？

score 125 · Accepted Answer

You can do it quite easily with (introduced in PostgreSQL 8.2) VALUES (), ().

Syntax will be like this:

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

score 85 · Accepted Answer

In Postgres 9.4 or later, this is simplest and fastest:

SELECT c.*
FROM   comments c
JOIN   unnest('{1,3,2,4}'::int[]) WITH ORDINALITY t(id, ord) USING (id)
ORDER  BY t.ord;

WITH ORDINALITY was introduced with in Postgres 9.4.
No need for a subquery, we can use the set-returning function like a table directly. (A.k.a. "table-function".)
A string literal to hand in the array instead of an ARRAY constructor may be easier to implement with some clients.
For convenience (optionally), copy the column name we are joining to (id in the example), so we can join with a short USING clause to only get a single instance of the join column in the result.
Works with any input type. If your key column is of type text, provide something like '{foo,bar,baz}'::text[].

Detailed explanation:

PostgreSQL unnest() with element number

score 73 · Accepted Answer

Just because it is so difficult to find and it has to be spread: in mySQL this can be done much simpler, but I don't know if it works in other SQL.

SELECT * FROM `comments`
WHERE `comments`.`id` IN ('12','5','3','17')
ORDER BY FIELD(`comments`.`id`,'12','5','3','17')

score 56 · Accepted Answer

With Postgres 9.4 this can be done a bit shorter:

select c.*
from comments c
join (
  select *
  from unnest(array[43,47,42]) with ordinality
) as x (id, ordering) on c.id = x.id
order by x.ordering;

Or a bit more compact without a derived table:

select c.*
from comments c
  join unnest(array[43,47,42]) with ordinality as x (id, ordering) 
    on c.id = x.id
order by x.ordering

Removing the need to manually assign/maintain a position to each value.

With Postgres 9.6 this can be done using array_position():

with x (id_list) as (
  values (array[42,48,43])
)
select c.*
from comments c, x
where id = any (x.id_list)
order by array_position(x.id_list, c.id);

The CTE is used so that the list of values only needs to be specified once. If that is not important this can also be written as:

select c.*
from comments c
where id in (42,48,43)
order by array_position(array[42,48,43], c.id);

score 50 · Accepted Answer

I think this way is better :

SELECT * FROM "comments" WHERE ("comments"."id" IN (1,3,2,4))
    ORDER BY  id=1 DESC, id=3 DESC, id=2 DESC, id=4 DESC

score 30 · Accepted Answer

Another way to do it in Postgres would be to use the idx function.

SELECT *
FROM comments
ORDER BY idx(array[1,3,2,4], comments.id)

Don't forget to create the idx function first, as described here: http://wiki.postgresql.org/wiki/Array_Index

score 27 · Accepted Answer

In Postgresql:

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

score 2 · Accepted Answer

在对此进行更多研究时，我发现了这个解决方案：

SELECT * FROM "comments" WHERE ("comments"."id" IN (1,3,2,4)) 
ORDER BY CASE "comments"."id"
WHEN 1 THEN 1
WHEN 3 THEN 2
WHEN 2 THEN 3
WHEN 4 THEN 4
END

然而，这似乎相当冗长，并且可能在大型数据集上存在性能问题。任何人都可以对这些问题发表评论吗？

score 2 · Accepted Answer

为此，我认为您可能应该有一个额外的“ORDER”表，它定义了 ID 到订单的映射（有效地按照您对自己问题的回答），然后您可以将其用作您选择的附加列然后你可以排序。

通过这种方式，您可以在数据库中明确描述您想要的顺序，它应该在哪里。

score 2 · Accepted Answer

sans SEQUENCE, works only on 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

score 1 · Accepted Answer

SELECT * FROM "comments" JOIN (
  SELECT 1 as "id",1 as "order" UNION ALL 
  SELECT 3,2 UNION ALL SELECT 2,3 UNION ALL SELECT 4,4
) j ON "comments"."id" = j."id" ORDER BY j.ORDER

或者如果你更喜欢邪恶而不是善良：

SELECT * FROM "comments" WHERE ("comments"."id" IN (1,3,2,4))
ORDER BY POSITION(','+"comments"."id"+',' IN ',1,3,2,4,')

score 0 · Accepted Answer

create sequence serial start 1;

select * from comments c
join (select unnest(ARRAY[1,3,2,4]) as id, nextval('serial') as id_sorter) x
on x.id = c.id
order by x.id_sorter;

drop sequence serial;

[编辑]

unnest is not yet built-in in 8.3, but you can create one yourself(the beauty of any*):

create function unnest(anyarray) returns setof anyelement
language sql as
$$
    select $1[i] from generate_series(array_lower($1,1),array_upper($1,1)) i;
$$;

that function can work in any type:

select unnest(array['John','Paul','George','Ringo']) as beatle
select unnest(array[1,3,2,4]) as id

score 0 · Accepted Answer

And here's another solution that works and uses a constant table (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

But again I'm not sure that this is performant.

I've got a bunch of answers now. Can I get some voting and comments so I know which is the winner!

Thanks All :-)

score 0 · Accepted Answer

Slight improvement over the version that uses a sequence I think:

CREATE OR REPLACE FUNCTION in_sort(anyarray, out id anyelement, out ordinal int)
LANGUAGE SQL AS
$$
    SELECT $1[i], i FROM generate_series(array_lower($1,1),array_upper($1,1)) i;
$$;

SELECT 
    * 
FROM 
    comments c
    INNER JOIN (SELECT * FROM in_sort(ARRAY[1,3,2,4])) AS in_sort
        USING (id)
ORDER BY in_sort.ordinal;

score 0 · Accepted Answer

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)

here, [bbs] is the main table that has a field called ids, and, ids is the array that store the comments.id .

passed in postgresql 9.6

score 0 · Accepted Answer

Lets get a visual impression about what was already said. For example you have a table with some tasks:

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

And you want to order the list of tasks by its status. The status is a list of string values:

(processing, pending,  completed, deleted)

The trick is to give each status value an interger and order the list numerical:

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;

Which leads to:

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

Credit @user80168

score -2 · Accepted Answer

我同意所有其他说“不要那样做”或“SQL 不擅长那样”的海报。如果您想按评论的某些方面进行排序，则将另一个整数列添加到您的一个表中以保存您的排序标准并按该值排序。例如“ORDER BY comments.sort DESC” 如果你想每次都以不同的顺序对它们进行排序，那么……在这种情况下，SQL 不适合你。

sql - 按 IN 值列表排序

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