Get rank in a score table - mysql

Question

how to rank in myqsl?
sample code:
SELECT
contestant_tbl.contestant_num,
contestant_tbl.fn,
contestant_tbl.ln,
tally_j1_tbl.c1_score + tally_j1_tbl.c2_score AS j1_total,
tally_j2_tbl.c1_score + tally_j2_tbl.c2_score AS j2_total
FROM
contestant_tbl
LEFT JOIN tally_j1_tbl ON contestant_tbl.contestant_num = tally_j1_tbl.contestant_num
LEFT JOIN tally_j2_tbl ON contestant_tbl.contestant_num = tally_j2_tbl.contestant_num
GROUP BY
contestant_tbl.contestant_num
i wanted to have an additional column total and rank.

Answer 1

Hope this is what you are looking for.
SELECT
contestant_tbl.contestant_num,
contestant_tbl.fn,
contestant_tbl.ln,
tally_j1_tbl.c1_score + tally_j1_tbl.c2_score AS j1_total,
tally_j2_tbl.c1_score + tally_j2_tbl.c2_score AS j2_total
j1_total + j2_total AS total,
RANK () OVER (
ORDER BY total DESC
) rank
FROM
contestant_tbl
LEFT JOIN tally_j1_tbl ON contestant_tbl.contestant_num = tally_j1_tbl.contestant_num
LEFT JOIN tally_j2_tbl ON contestant_tbl.contestant_num = tally_j2_tbl.contestant_num
GROUP BY
contestant_tbl.contestant_num

Answer 2

We cannot guess your database structure according to your question. However, there are couple of noticeable issues.
Please take a look at the corrected query (rankings included):
set #num = 0;
SELECT
contestant_tbl.contestant_num,
contestant_tbl.fn,
contestant_tbl.ln,
sum(coalesce(tally_j1_tbl.c1_score, 0)) + sum(coalesce(tally_j1_tbl.c2_score, 0)) AS j1_total,
sum(coalesce(tally_j2_tbl.c1_score, 0)) + sum(coalesce(tally_j2_tbl.c2_score, 0)) AS j2_total,
sum(coalesce(tally_j1_tbl.c1_score, 0)) + sum(coalesce(tally_j1_tbl.c2_score, 0)) + sum(coalesce(tally_j2_tbl.c1_score, 0)) + sum(coalesce(tally_j2_tbl.c2_score, 0)) AS total,
#num := #num + 1 as pos
FROM
contestant_tbl
LEFT JOIN tally_j1_tbl ON contestant_tbl.contestant_num = tally_j1_tbl.contestant_num
LEFT JOIN tally_j2_tbl ON contestant_tbl.contestant_num = tally_j2_tbl.contestant_num
GROUP BY
contestant_tbl.contestant_num
ORDER BY
sum(coalesce(tally_j1_tbl.c1_score, 0)) + sum(coalesce(tally_j1_tbl.c2_score, 0)) + sum(coalesce(tally_j2_tbl.c1_score, 0)) + sum(coalesce(tally_j2_tbl.c2_score, 0))
Numerical values that can be NULL should be coalesced prior sum opperation. (e.g. coalesce(tally_j2_tbl.c2_score, 0)).
Your query contains group by, but doesn't contain any aggregate function. I assume that sum should be used.
Ranking is achieved by utilizing MySQL variables. It is for older MySQL versions. MySQL 8 introduced RANK function so it is easier and cleaner:
SELECT
contestant_tbl.contestant_num,
contestant_tbl.fn,
contestant_tbl.ln,
sum(coalesce(tally_j1_tbl.c1_score, 0)) + sum(coalesce(tally_j1_tbl.c2_score, 0)) AS j1_total,
sum(coalesce(tally_j2_tbl.c1_score, 0)) + sum(coalesce(tally_j2_tbl.c2_score, 0)) AS j2_total,
sum(coalesce(tally_j1_tbl.c1_score, 0)) + sum(coalesce(tally_j1_tbl.c2_score, 0)) + sum(coalesce(tally_j2_tbl.c1_score, 0)) + sum(coalesce(tally_j2_tbl.c2_score, 0)) AS total,
RANK() OVER (
ORDER BY sum(coalesce(tally_j1_tbl.c1_score, 0)) + sum(coalesce(tally_j1_tbl.c2_score, 0)) + sum(coalesce(tally_j2_tbl.c1_score, 0)) + sum(coalesce(tally_j2_tbl.c2_score, 0))
) as pos
FROM
contestant_tbl
LEFT JOIN tally_j1_tbl ON contestant_tbl.contestant_num = tally_j1_tbl.contestant_num
LEFT JOIN tally_j2_tbl ON contestant_tbl.contestant_num = tally_j2_tbl.contestant_num
GROUP BY
contestant_tbl.contestant_num
ORDER BY
sum(coalesce(tally_j1_tbl.c1_score, 0)) + sum(coalesce(tally_j1_tbl.c2_score, 0)) + sum(coalesce(tally_j2_tbl.c1_score, 0)) + sum(coalesce(tally_j2_tbl.c2_score, 0))