select s.s_name , s.s_birth ,s.s_sex,sc.s_score from (select s_id, c_id, s_score, row_number() over(distribute by c_id sort by s_score desc) rowNum from score) sc left join student s on s.s_id = sc.s_id where sc.rowNum between 2 and 3;
时间: 2024-02-19 13:03:17 浏览: 129
这是一个 SQL 查询语句,用于查询学生表和成绩表中的信息。具体来说,它使用了子查询和窗口函数,以及左连接和条件筛选。
子查询部分是:
```
select s_id, c_id, s_score,
row_number() over(distribute by c_id sort by s_score desc) rowNum
from score
```
这个子查询用于给每个课程按照成绩从高到低排序,并为每个学生的排名添加一个行号。其中,`distribute by c_id` 表示按照课程 ID 进行分组,`sort by s_score desc` 表示按照成绩倒序排序。
主查询部分是:
```
select s.s_name, s.s_birth, s.s_sex, sc.s_score
from (子查询) sc
left join student s on s.s_id = sc.s_id
where sc.rowNum between 2 and 3
```
这个主查询使用了左连接,将学生表和子查询结果按照学生 ID 进行连接,并筛选出排名为第二和第三的学生信息。最终,查询结果包括学生姓名、出生日期、性别和对应课程的成绩。
相关问题
select s.s_id,s_name,avg(sc2.s_score) from student s join (select sc1.s_id,count(sc1.s_id) cc from score sc1 where sc1.s_score<60 group by sc1.s_id having cc>=2) t on s.s_id =t.s_id join score sc2 on s.s_id =sc2.s_id; 报SQL 错误 [10025] [42000]: Error while compiling statement: FAILED: SemanticException [Error 10025]: Line 1:7 Expression not in GROUP BY key 's_id'帮我修改一下
根据错误信息,查询语句中的表达式 's_id' 不在 GROUP BY key 中,因此需要将其添加到 GROUP BY 子句中。下面是修改后的 SQL 查询语句:
```
SELECT s.s_id, s.s_name, AVG(sc2.s_score)
FROM student s
JOIN (
SELECT sc1.s_id, COUNT(sc1.s_id) cc
FROM score sc1
WHERE sc1.s_score < 60
GROUP BY sc1.s_id
HAVING cc >= 2
) t ON s.s_id = t.s_id
JOIN score sc2 ON s.s_id = sc2.s_id
GROUP BY s.s_id, s.s_name;
```
修改后,查询语句会按照 s_id 和 s_name 进行分组,从而解决了错误信息中提到的问题。
优化这段代码select * from score sc where (select sc.s_score from score sc where sc.c_id = 01) > (select sc.s_score from score sc where sc.c_id = 02)
这段代码的查询逻辑可以进行优化,可以使用JOIN语句代替子查询,同时使用WHERE子句进行筛选,如下所示:
```
SELECT sc.* FROM score sc
JOIN score sc2 ON sc.s_id = sc2.s_id
WHERE sc.c_id = 01 AND sc2.c_id = 02 AND sc.s_score > sc2.s_score
```
这样可以提高查询效率,并且语句更加简洁易懂。
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