score表:
create
table
`score` (
`student_id`
int(10) default
null,
`class_id`
int(10) default
null,
`score`
int(5) default
null
) engine=innodb default charset=utf8mb4 collate=utf8mb4_unicode_ci
資料準備:
insert
into score values(1,1,100),(2,1,93),(3,1,89),(4,1,96),(5,2,98),(6,2,97),(7,2,90),(8,2,88),(9,1,96);
mysql> select * from score;
+------------+----------+-------+
| student_id | class_id | score |
+------------+----------+-------+
| 1 | 1 | 100 |
| 2 | 1 | 93 |
| 3 | 1 | 89 |
| 4 | 1 | 96 |
| 5 | 2 | 98 |
| 6 | 2 | 97 |
| 7 | 2 | 90 |
| 8 | 2 | 88 |
| 9 | 1 | 96 |
+------------+----------+-------+
9 rows in set (0.00 sec)
mysql> select * from score s1 where (select count(0) from score s2 where s1.class_id = s2.class_id and s1.score < s2.score) < 2;
+------------+----------+-------+
| student_id | class_id | score |
+------------+----------+-------+
| 1 | 1 | 100 |
| 4 | 1 | 96 |
| 5 | 2 | 98 |
| 6 | 2 | 97 |
| 9 | 1 | 96 |
+------------+----------+-------+
5 rows in set (0.00 sec)
或者使用 left join 的方式:
mysql> select s1.* from score s1 left join score s2 on s1.class_id = s2.class_id and s1.score| student_id | class_id | score |
+------------+----------+-------+
| 1 | 1 | 100 |
| 4 | 1 | 96 |
| 9 | 1 | 96 |
| 5 | 2 | 98 |
| 6 | 2 | 97 |
+------------+----------+-------+
5 rows in set (0.00 sec)
mysql> select s1.*,(select count(0) + 1 from score s2 where s2.score > s1.score)rank from score s1;
+------------+----------+-------+------+
| student_id | class_id | score | rank |
+------------+----------+-------+------+
| 1 | 1 | 100 | 1 |
| 2 | 1 | 93 | 6 |
| 3 | 1 | 89 | 8 |
| 4 | 1 | 96 | 4 |
| 5 | 2 | 98 | 2 |
| 6 | 2 | 97 | 3 |
| 7 | 2 | 90 | 7 |
| 8 | 2 | 88 | 9 |
| 9 | 1 | 96 | 4 |
+------------+----------+-------+------+
9 rows in set (0.00 sec)
3.取學生成績資料,表示班級排名
mysql> select s1.*,(select count(0) + 1 from score s2 where s1.class_id = s2.class_id and s2.score > s1.score)rank from score s1 order by class_id,rank;
+------------+----------+-------+------+
| student_id | class_id | score | rank |
+------------+----------+-------+------+
| 1 | 1 | 100 | 1 |
| 4 | 1 | 96 | 2 |
| 9 | 1 | 96 | 2 |
| 2 | 1 | 93 | 4 |
| 3 | 1 | 89 | 5 |
| 5 | 2 | 98 | 1 |
| 6 | 2 | 97 | 2 |
| 7 | 2 | 90 | 3 |
| 8 | 2 | 88 | 4 |
+------------+----------+-------+------+
9 rows in set (0.00 sec)
4.取每個班級前兩名(並列的只取前面的資料)
參考文件:
學生成績排名
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