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在8.3中还没有内置，但你可以自己创建一个(任何的美丽*):

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

该函数可以在任何类型下工作:

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

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

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:-)

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在8.3中还没有内置，但你可以自己创建一个(任何的美丽*):

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

该函数可以在任何类型下工作:

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

在Postgresql:

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

我认为这样比较好:

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