Leetcode MySQL database topic 178

178. Rank Scores

１、 Questions and answers

Write a SQL query to rank scores. If there is a tie between two scores, both should have the same ranking. Note that after a tie, the next ranking number should be the next consecutive integer value. In other words, there should be no “holes” between ranks.

To write SQL Query to sort scores . If two scores are equal , Then both should have the same ranking . Please note that , After equality , The next rank number should be the next consecutive integer value . let me put it another way , Equal scores juxtapose .
Table:Scores

+----+-------+
| Id | Score |
+----+-------+
| 1  | 3.50  |
| 2  | 3.65  |
| 3  | 4.00  |
| 4  | 3.85  |
| 5  | 4.00  |
| 6  | 3.65  |
+----+-------+

For example, given the above Scores table, your query should generate the following report (order by highest score):

for example , Give the above “Scores” surface , Your query should generate the following report （ Sort by highest score )

+-------+------+
| Score | Rank |
+-------+------+
| 4.00  | 1    |
| 4.00  | 1    |
| 3.85  | 2    |
| 3.65  | 3    |
| 3.65  | 3    |
| 3.50  | 4    |
+-------+------+

answer ：
select
Score,
(select count(distinct b.Score) from scores b where b.Score >= s.Score) as Rank
from scores s
order by Score desc

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２、 Summary of knowledge points

Verification steps ：

Create and insert tables scores
create table scores(
Id int NULL,
Score double NULL
);
insert into scores
values(1,3.5),(2,3.65),(3,4.00),(4,3.85),(5,4.00),(6,3.65);


Execute the answer ：

+-------+------+
| Score | Rank |
+-------+------+
|     4 |    1 |
|     4 |    1 |
|  3.85 |    2 |
|  3.65 |    3 |
|  3.65 |    3 |
|   3.5 |    4 |
+-------+------+
6 rows in set (0.00 sec)

Knowledge point ：

• Subquery and where Screening
• select count( distinct id ) from table_name Calculation talbebname In the table id How many different records