mysql grouped ranking with ties - mysql

Question

so i have data in a table like this:
id total group_id
1897 738 1
2489 716 2
2325 715 3
1788 702 2
1707 699 3
2400 688 3
2668 682 2
1373 666 1
1494 666 1
1564 660 1
2699 659 1
1307 648 4
1720 645 4
2176 644 1
1454 644 4
2385 639 3
1001 634 2
2099 634 4
1006 632 1
2587 630 3
1955 624 3
1827 624 4
2505 623 4
2062 621 3
1003 618 1
2286 615 4
2722 609 4
how can i rank the ids per group based on the total and giving the same rank when there is a tie?
i have tried this solution below but it doesnt take care of the ties.
SELECT g1.admission_no
, g1.total
, g1.stream_id
, COUNT(*) AS rn
FROM ranktest AS g1
JOIN ranktest AS g2
ON (g2.total, g2.admission_no) >= (g1.total, g1.admission_no)
AND g1.stream_id = g2.stream_id
GROUP BY g1.admission_no
, g1.stream_id
, g1.total
ORDER BY g1.stream_id
, total ;
expected
id total group_id rank
1897 738 1 1
2489 716 2 1
2325 715 3 1
1788 702 2 2
1707 699 3 2
2400 688 3 3
2668 682 2 3
1373 666 1 2
1494 666 1 2
1564 660 1 3
2699 659 1 4
1307 648 4 1
1720 645 4 2
2176 644 1 4
1454 644 4 3
2385 639 3 4
1001 634 2 4
2099 634 4 4
1006 632 1 5
2587 630 3 5
1955 624 3 6
1827 624 4 5
2505 623 4 6
2062 621 3 6
1003 618 1 6
2286 615 4 7
2722 609 4 8

Answer 1

If original order is not very important you can start from:
http://sqlfiddle.com/#!9/a15a2/10
SELECT
ranktest.*,
IF(#rank IS NULL,#rank:=1, IF(#prev!=group_id,#rank:=1,#rank:=#rank+1) ) rank,
#prev:=group_id
FROM ranktest
ORDER BY group_id, total
but keep in mind that this is not very efficient query from performance perspective.

Answer 2

From the MySQL Manual Page entitled User-Defined Variables:
In the following statement, you
might think that MySQL will evaluate #a first and then do an
assignment second:
SELECT #a, #a:=#a+1, ...;
However, the order of evaluation for expressions involving user
variables is undefined.
This is why so few people write these answers correctly and safely. The object is not to hit the desired results once, but to do so again and again in real-world environments using best practices and guaranteed results.
If you don't read the Obligatory Doc, and implement it, your results are not guaranteed. There is no lazy way to do this and one shouldn't even bother :p
select id,total,group_id,rank
from
( select id,total,group_id,
#rn:=if( group_id!=#curr_grp, greatest(#grp_rank:=1,0),
if(total=#prev_grp_total,#grp_rank,greatest(#grp_rank:=#grp_rank+1,0) ) ) as rank,
#curr_grp:=group_id,
#prev_grp_total:=total
from trans01
cross join (select #grp_rank:=0,#curr_grp:=0,#prev_grp_total:=-1) xParams
order by group_id,total desc
)xDerived;
+------+-------+----------+------+
| id | total | group_id | rank |
+------+-------+----------+------+
| 1897 | 738 | 1 | 1 |
| 1373 | 666 | 1 | 2 |
| 1494 | 666 | 1 | 2 |
| 1564 | 660 | 1 | 3 |
| 2699 | 659 | 1 | 4 |
| 2176 | 644 | 1 | 5 |
| 1006 | 632 | 1 | 6 |
| 1003 | 618 | 1 | 7 |
| 2489 | 716 | 2 | 1 |
| 1788 | 702 | 2 | 2 |
| 2668 | 682 | 2 | 3 |
| 1001 | 634 | 2 | 4 |
| 2325 | 715 | 3 | 1 |
| 1707 | 699 | 3 | 2 |
| 2400 | 688 | 3 | 3 |
| 2385 | 639 | 3 | 4 |
| 2587 | 630 | 3 | 5 |
| 1955 | 624 | 3 | 6 |
| 2062 | 621 | 3 | 7 |
| 1307 | 648 | 4 | 1 |
| 1720 | 645 | 4 | 2 |
| 1454 | 644 | 4 | 3 |
| 2099 | 634 | 4 | 4 |
| 1827 | 624 | 4 | 5 |
| 2505 | 623 | 4 | 6 |
| 2286 | 615 | 4 | 7 |
| 2722 | 609 | 4 | 8 |
+------+-------+----------+------+

Answer 3

came up with this answer after googling a bit..not sure is its the best but it works for my case:
SELECT id, group_id, total,
#std:=CASE WHEN #grp <> group_id THEN concat(left(#grp:=group_id, 0), 1) ELSE if(#prev=total,#std,#std+1) END AS rn,#prev:=total
FROM
(SELECT #std:= -1) s,
(SELECT #grp:= -1,#prev:=null) c,
(SELECT *
FROM table
ORDER BY group_id, total desc
) s