Question

我有一张叫做竞赛的桌子：

+-------+-------+------+
| name  | Points | Rank |
+-------+-------+------+
| Stud1 |    50 |    0 |
| Stud2 |    40 |    0 |
| Stud3 |    20 |    0 |
| Stud4 |    20 |    0 |
| Stud5 |    15 |    0 |
| Stud6 |    10 |    0 |
+-------+-------+------+

点数列将继续使用点进行更新，并根据点数生成等级。

请帮我这样做。

我试过这个http://stackoverflow.com/a/1320196/1816093

Answer 1

不要存储排名。只需动态计算......

DROP TABLE IF EXISTS my_table;

CREATE TABLE my_table
(name VARCHAR(12) PRIMARY KEY,points INT NOT NULL);

INSERT INTO my_table VALUES
('Stud1',50),
('Stud2',40),
('Stud3',20),
('Stud4',20),
('Stud5',15),
('Stud6',10);

解决方案1：

SELECT x.*
     , FIND_IN_SET(points,(SELECT GROUP_CONCAT(DISTINCT points ORDER BY points DESC) FROM my_table)) n 
  FROM my_table x;
+-------+--------+------+
| name  | points | n    |
+-------+--------+------+
| Stud1 |     50 |    1 |
| Stud2 |     40 |    2 |
| Stud3 |     20 |    3 |
| Stud4 |     20 |    3 |
| Stud5 |     15 |    4 |
| Stud6 |     10 |    5 |
+-------+--------+------+

解决方案2：

SELECT x.*
     , CASE WHEN @prev = points THEN @i:=@i ELSE @i:=@i+1 END rank
     , @prev := points FROM my_table x
     , (SELECT @prev:=null,@i:=0) vars 
 ORDER 
    BY points
     , name;
+-------+--------+------+-----------------+
| name  | points | rank | @prev := points |
+-------+--------+------+-----------------+
| Stud6 |     10 |    1 |              10 |
| Stud5 |     15 |    2 |              15 |
| Stud3 |     20 |    3 |              20 |
| Stud4 |     20 |    3 |              20 |
| Stud2 |     40 |    4 |              40 |
| Stud1 |     50 |    5 |              50 |
+-------+--------+------+-----------------+

Mysql根据分数

1 个答案: