MySQL query to get best Ranks from one table and UPDATE with results another

Question

I have a Ranking board for the best first 100 blogs for each gender Males and Females.

I have a blogs table:

PRIMARY
blogs_id  users_id  blogs_score  blo         


        

Answer 1

UPDATE users u, (
SELECT 
( 
    CASE gender 
    WHEN @curType 
    THEN @curRow := @curRow + 1 
    ELSE @curRow := 1 AND @curType := gender END
) + 1 AS rank, users_id, blogs_score, blogs_score_time, gender 
FROM blogs, 
(SELECT @curRow := 0, @curType := '') r
ORDER BY gender, blogs_score DESC, blogs_score_time DESC
) r1
SET u.best_rank = r1.rank
WHERE
u.id = r1.users_id

It does 2 works:

1. inner select query generates rank as per gender, score and time
2. updates user table with respective rank.

Answer 2

I think you should add the a GROUP BY clause this way before ORDER BY

$sql->query("UPDATE users
              JOIN (SELECT b.users_id,
                         @curRank := @curRank + 1 AS rank,
                         MAX(b.blogs_score), MAX(b.blogs_score_time   )
                  FROM blogs b
                         JOIN (SELECT @curRank := 0) r
                  GROUP BY b.user_id, rank
                  ORDER BY  b.blogs_score DESC, p.blogs_score_time DESC LIMIT 100
                 ) ranks ON (ranks.users_id = users.id)
            SET users.best_rank = ranks.rank");