MySQL sort after argument in IN()

Question

I have string containing a lot of IDs corresponding to my database. Like:

1,2,3,4,5

I then do a mySQL query to select all those rows:

Answer 1

you want the find_in_set function

$list = "1,2,....";
$sql = "select * from table where id in($list) order by find_in_set($id, '$list')";

another (probably faster) option is to do sorting in php:

$list = array(2, 3, ...);
$s    = implode(',', $list);
$sth  = mysql_query("select * from table where id in($s)");

$rows = array();
while($r = mysql_fetch_object($sth))
    $rows[$r->id] = $r;

$sorted_rows = array();
foreach($list as $id)
   $sorted_rows[] = $rows[$id];

Answer 2

You might use order by with case ... end, though part between case and end should be generated by PHP:

select
    *    
from
    table
where
    id in (2, 1, 3, 4, 5)
order by
    case id
        when 2 then 1
        when 1 then 2
        when 3 then 3
        when 4 then 4
        when 5 then 5
    end asc

Answer 3

You should be able to do this via the FIELD() function like so:

SELECT * FROM `table` WHERE `id` IN (2,1,3,4,5) ORDER BY FIELD(`id`, 2,1,3,4,5) DESC

That is:

SELECT
  *
FROM
  `table`
WHERE
  `id` IN (".$myIDs.")
ORDER BY
  FIELD(`id`, ".$myIDs.") DESC

More in this blog post: Sorting MySQL rows using column values.

Answer 4

Another option, though FIELD is probably the way to go in your case:

SELECT * FROM `table` WHERE `id` IN (2,1,3,4,5) ORDER BY `id` = 2 DESC, `id` = 1 DESC,`id` = 3 DESC, `id` = 4 DESC, `id` = 5 DESC