Implement Dense Rank In Mysql

Mysql : Dense_rank

SELECT id,
  @rnk:=IF(@preval <=> score, @rnk, @row + 1) AS dns_rnk,
  @row:= @row+1 AS rnk,
  @preval:=score as score
FROM table
# be careful for NULL handling.
# if all the values of score column are null, then dns_rank will zero.
# please set proper initial value for @preval based on your data.
JOIN (SELECT @rnk := 0, @preval :=null, @row := 0) r
ORDER BY score DESC