Q:

MySQL: order by sum

I have article table
`id`,
`article_id`,
`stage_1_point`,
`stage_2_point`

I need top 10 articles based on 
(stage_1_point+stage_2_point),

in the list and when i view any article i need to show its place. 
My question is how can show its place without using order by. 

A:

USE ORDER BY (stage_1_point+stage_2_point) DESC
So, It will be like
SELECT `id`,
`article_id`,
`stage_1_point`,
`stage_2_point`
FROM YOUR_TABLE ORDER BY (stage_1_point+stage_2_point) DESC
LIMIT 0,10

UPDATE
As OP stated, he/she needs to know the position of specific article. 
SELECT * FROM (SELECT `id`,
`article_id`,
`stage_1_point`,
`stage_2_point`,
 @curRank := @curRank + 1 AS rank
FROM YOUR_TABLE, (SELECT @curRank := 0) r ORDER BY      
(stage_1_point+stage_2_point) DESC) TAB
WHERE `article_id`=10

Above query will return rows for article_id 10, which will have a column Rank which tells the position of the article.