select a.s_id ,a.s_name ,count(b.c_id) as sum_course ,sum(b.s_score)as sum_score from student a left join score b on a.s_id=b.s_id GROUP BY a.s_id,a.s_name

Sure! Here is the SQL query to fulfill your request:

SELECT a.s_id, a.s_name, COUNT(b.c_id) AS sum_course, SUM(b.s_score) AS sum_score
FROM student a
LEFT JOIN score b ON a.s_id = b.s_id
GROUP BY a.s_id, a.s_name;

This query will retrieve the student ID (`s_id`), student name (`s_name`), the total number of courses taken by each student (`sum_course`), and the sum of scores obtained by each student (`sum_score`). The `LEFT JOIN` ensures that all students are included in the result, even if they don't have any scores recorded in the `score` table.

Let me know if you need any further assistance!

相关问题

select a.* ,b.s_score as 01_score,c.s_score as 02_score from student a join score b on a.s_id=b.s_id and b.c_id='01' left join score c on a.s_id=c.s_id and c.c_id='02' or c.c_id = NULL where b.s_score>c.s_score

你好!根据您的要求，我理解您需要执行一个查询语句，选择学生表中的所有列，并将 b 表中的 s_score 列作为 '01_score'，将 c 表中的 s_score 列作为 '02_score'。查询条件是 b 表中的 s_score 大于 c 表中的 s_score。同时，使用左连接将 c 表与 a 表关联起来，并且 c 表中的 c_id 值为 '02' 或者为 NULL。以下是相应的 SQL 语句：

SELECT a.*, b.s_score AS '01_score', c.s_score AS '02_score'
FROM student a
JOIN score b ON a.s_id = b.s_id AND b.c_id = '01'
LEFT JOIN score c ON a.s_id = c.s_id AND (c.c_id = '02' OR c.c_id IS NULL)
WHERE b.s_score > c.s_score

请注意，以上 SQL 语句仅是根据您的问题所提供的信息编写的，如果有其他条件或要求，请提供更详细的信息。

解释一下sql语句的作用：SELECT * FROM student AS a INNER JOIN score AS b ON a.s_id = b.s_id INNER JOIN score AS c ON a.s_id = c.s_id AND b.c_id = 1 AND c.c_id = 2 WHERE b.s_score > c.s_score;

这个 SQL 语句的作用是从两个表（`student` 和 `score`）中选择数据，并进行多个表的内连接（`INNER JOIN`）。下面是对这个 SQL 语句的逐步解释：

1. `SELECT *`: 表示选择所有列的数据。
2. `FROM student AS a`: 从名为 `student` 的表中选择数据，并将其别名设置为 `a`，以便在后续的查询中引用它。
3. `INNER JOIN score AS b ON a.s_id = b.s_id`: 将 `student` 表和 `score` 表通过 `s_id` 列进行内连接。这意味着只有在两个表中具有相同 `s_id` 值的行才会被包括在结果中。
4. `INNER JOIN score AS c ON a.s_id = c.s_id AND b.c_id = 1 AND c.c_id = 2`: 将之前连接的结果和 `score` 表再次进行内连接。这次连接需要满足三个条件：`a.s_id = c.s_id`、`b.c_id = 1` 和 `c.c_id = 2`。该条件限制了连接结果中 `b.c_id` 为 1，`c.c_id` 为 2 的行。
5. `WHERE b.s_score > c.s_score`: 在连接的结果中，只选择满足条件 `b.s_score > c.s_score` 的行。这个条件要求了 `b` 表中的 `s_score` 必须大于 `c` 表中的 `s_score`。

综上所述，该 SQL 语句的作用是从 `student` 表中选择与 `score` 表中的两个特定条件相关联的数据，并且只选择满足条件 `b.s_score > c.s_score` 的行。