ORDER BY CASE ...

Am I misusing the ORDER BY with CASE, or, what? :)

I have a table, messages, half dozen of columns, exposing here just
three of them:

pulitzer2=# select id, "from", receiving_time from messages where
service_id = 20 order by case when 5=5 then 2 else 3 end desc limit 5;
id | from | receiving_time
--------+---------------+------------------------
869585 | +385989095824 | 2005-12-08 16:04:23+01
816579 | +385915912312 | 2005-11-23 17:51:06+01
816595 | +38598539263 | 2005-11-23 17:58:21+01
816594 | +385915929232 | 2005-11-23 17:57:30+01
816589 | +385912538567 | 2005-11-23 17:54:32+01
(5 rows)

pulitzer2=# select id, "from", receiving_time from messages where
service_id = 20 order by case when 5=6 then 2 else 3 end desc limit 5;
id | from | receiving_time
--------+---------------+------------------------
869585 | +385989095824 | 2005-12-08 16:04:23+01
816579 | +385915912312 | 2005-11-23 17:51:06+01
816595 | +38598539263 | 2005-11-23 17:58:21+01
816594 | +385915929232 | 2005-11-23 17:57:30+01
816589 | +385912538567 | 2005-11-23 17:54:32+01
(5 rows)

I tought I'd get differently sorted data, since in the first query I
said 5=5, and in second I said 5=6.

Is this a right way to use CASE on ORDER BY, or? I need to sord the data
in the function depending on the function parametar. If it's true,
randomize the sort, if not, sort by receiving_time, newest first.

So, can I do it with ORDER BY CASE ... END, or do I need to have two
querries, and then first check for the value of the parametar, and then,
according to that value, call the SELECTs wich sort randomly, or by
receiving_time.

Mario

P.S. The postgres is 8.1.2.
--
Mario Splivalo
Mob-Art
mario(dot)splivalo(at)mobart(dot)hr

"I can do it quick, I can do it cheap, I can do it well. Pick any two."