complex mysql rank !

Question

I have a table with these columns: win, los, id ...

I want to order the table by this index: win / ( win + los ) * 30 + win / SUM(win) * 70 and then to find the rank for two id's. I'm not very good on mysql, so what I wrote is totally wrong. (It uses Perl + DBI + DBD::mysql):

$stmt=$con->prepare("SET @rk := 0");
$stmt=$con->prepare("SELECT rank, id FROM (
                           SELECT @rk := @rk + 1 AS rank,                
                                (win/(win+los)*30+win/SUM(win)*70) AS index,
                                win, los, id 
                          FROM tb_name ORDER BY index DESC) as result 
                   WHERE id=? AND id=?"); 
$stmt -> bind_param ("ii", $id1, $id2);
$stmt -> execute();
$stmt -> bind_result($rk, $idRk); 

And also this query it suppose to run maybe every 5-10 sec for every user, so I'm trying to find something very, very fast. If it's necessary I could add, change, delete any column, in order to be as fast as possible.

Answer 1

Whatever experession you use in the SELECT statement can also go into your ORDER BY expression.

You can also assign the expression a column alias and order by the alias, as you've done.

If you're not comfortable with mysql then I suggest you develop your query on its own rather than trying to embed it in a prepared statement at the same time.

Answer 2

Try this one:

SELECT rank, id FROM (
    SELECT @rk := @rk + 1 AS rank,                
    (win/(win+los)*30+win/win_sum*70) AS index, -- SUM(win) -> win_sum
    win, los, id 
    FROM tb_name,
    (SELECT SUM(win) as win_sum FROM tb_name) as ws -- separated SUM(win)
    ORDER BY index DESC) as result
WHERE id IN (?, ?);    -- id=? AND id=? will never happen, should be OR

A composite index on ('win', 'los') might be useful.