Original title: https://leetcode-cn.com/problems/rank-scores/
The problem-solving directory
writes a SQL query to achieve score ranking. If the two scores are the same, the two ranks are the same. Please note that the next place after the split should be the next consecutive integer value. In other words, there should be no "spacing" between rankings.
+----+-------+
| Id | Score |
+----+-------+
| 1 | 3.50 |
| 2 | 3.65 |
| 3 | 4.00 |
| 4 | 3.85 |
| 5 | 4.00 |
| 6 | 3.65 |
+----+-------+
For example, based on the Scores table given above, your query should return (in order of highest to lowest score):
+-------+------+
| Score | Rank |
+-------+------+
| 4.00 | 1 |
| 4.00 | 1 |
| 3.85 | 2 |
| 3.65 | 3 |
| 3.65 | 3 |
| 3.50 | 4 |
+-------+------+
1. The first solution
This question is very simple if you know dense_rank (); if you don't know it, it's a little difficult. (mySql does not have dense_rank (), oracle and hive do)
select
score as Score,
dense_rank() over(order by score desc) as Rank
from scores;
Let's vomit, I don't know why, there is a problem with the alias:
2. The second solution
Then talk about how mysql solves the problem, that is, the method without dense_rank ():
select
s1.score Score,
(select
count(distinct(s2.score))
from scores s2
where s2.score >= s1.score
) as Rank
from scores s1
order by Rank
This is quite interesting.
