Mysql rank with join table, result not true - mysql

Question

I have 2 table name table 'hasil' and table 'kat_soal' to join and give rank on each 'KatID' field on 'hasil' table..
here is my hasil table :
HasilID KatID UserID JBenar JSalah Nilai
15 1 1000 2 1 66.66666666666666
16 3 1000 2 0 100
17 1 1001 1 2 33.33333333333333
18 3 1001 1 1 50
19 1 1002 3 0 90
20 3 1002 2 0 80
and there is my kat_soal table
KatID Kategori Lama
1 IPA 30
2 IPS 30
3 Matematika 30
4 Bahasa Indonesia 20
5 Bahasa Inggris 20
this my query generate rank:
SELECT a.KatID,a.UserID,b.Kategori,c.Nama,a.JBenar,a.JSalah,ROUND(a.Nilai,2) as Nilai,
FIND_IN_SET( a.Nilai, l.list) AS rank
from hasil a
JOIN kat_soal b
ON a.KatID = b.KatID
JOIN datauser c
ON a.UserID=c.UserID
CROSS JOIN
(SELECT GROUP_CONCAT( a2.Nilai ORDER BY a2.Nilai DESC ) as list
FROM hasil a2) l
WHERE a.KatID='1'
ORDER BY a.Nilai DESC;
my result
//FOR KatID=1
KatID UserID Kategori Nama JBenar JSalah Nilai rank
1 1002 IPA ratam 3 0 90.00 2
1 1000 IPA Tarsan 2 1 66.67 4
1 1001 IPA wisnu 1 2 33.33 6
//FOR KatID=3
3 1000 Matematika Tarsan 2 0 100.00 1
3 1002 Matematika ratam 2 0 80.00 3
3 1001 Matematika wisnu 1 1 50.00 5
My Expected Result
//FOR KatID=1
KatID UserID Kategori Nama JBenar JSalah Nilai rank
1 1002 IPA ratam 3 0 90.00 1
1 1000 IPA Tarsan 2 1 66.67 2
1 1001 IPA wisnu 1 2 33.33 3
//FOR KatID=3
3 1000 Matematika Tarsan 2 0 100.00 1
3 1002 Matematika ratam 2 0 80.00 2
3 1001 Matematika wisnu 1 1 50.00 3
anyone can help me ?

Answer 1

Good example to solve the issue is by looking at: http://www.fromdual.com/ranking-mysql-results .
You are making this a bit complicated: First You take the value, making the value a string, then "finding position in string".
From the example it should be completely ok if it is done as (untested):
SET #rank=0;
SELECT a.KatID,a.UserID,b.Kategori,c.Nama,a.JBenar,a.JSalah,ROUND(a.Nilai,2) as Nilai,
#rank:=#rank+1 AS rank
from hasil a
JOIN kat_soal b
ON a.KatID = b.KatID
JOIN datauser c
ON a.UserID=c.UserID
WHERE a.KatID='1'
ORDER BY rank;
EDIT: Changed ordering - You are expecting to by ordered by rank in the final.
Below is the script without using table datauser for any1 to test:
SET #rank=0;
SELECT a.KatID,a.UserID,b.Kategori,a.JBenar,a.JSalah,ROUND(a.Nilai,2) as Nilai,
#rank:=#rank+1 AS rank
from hasil a
JOIN kat_soal b
ON a.KatID = b.KatID
WHERE a.KatID='1'
ORDER BY rank;