Re: Is it possible to make the order of output the same as the order of input parameters?

Thanks to all for the feedback. I keep getting impressed by how flexible
PostgreSQL is.

Any ideas which query should perform better? I put together all the
suggested approaches below.

== Approach 1 ==
SELECT c.*
FROM customer c, (VALUES

(1,23), (2,56),
(3, 2), (4,12),
(5,10)) x(ord,val)
WHERE c.id = x.val
ORDER BY x.ord;

== Approach 2 ==

SELECT
customer.*
FROM
customer a
JOIN (VALUES (1,23),(2,56),(3,2),(4,12),(5,10)) b
ON (a.id = b.column2)
ORDER BY b.column1

== Approach 3 ==

SELECT * FROM customer
WHERE id IN (23, 56, 2, 12, 10)
ORDER BY POSITION(':' || id || ':' IN ':23:56:2:12:10:');

== Approach 4 ==
WITH
t(a) AS (VALUES (ARRAY[23, 56, 2, 12, 10])),
s(i) AS (SELECT generate_subscripts((SELECT a FROM t)::integer[], 1))
SELECT i, a[i]
FROM s CROSS JOIN t;

On Wed, Jun 2, 2010 at 7:43 AM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:

> * m. hvostinski (makhvost(at)gmail(dot)com) wrote:
> > I have a simple query like:
> >
> > SELECT * FROM customer WHERE id IN (23, 56, 2, 12, 10)
> >
> > The problem is that I need to retrieve the rows in the same order as the
> set
> > of ids provided in the select statement. Can it be done?
>
> Not very easily. My first thought would be doing something like:
>
> SELECT
> customer.*
> FROM
> customer a
> JOIN (VALUES (1,23),(2,56),(3,2),(4,12),(5,10)) b
> ON (a.id = b.column2)
> ORDER BY b.column1
> ;
>
> Thanks,
>
> Stephen
>
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