在分组依据之后检查每个分组的两列是否相同

Question

假设一个数据库有两个表：

1。表SC：

+------+------+-------+
| sid  | cid  | score |
+------+------+-------+
| 01   | 01   |  80.0 |
| 01   | 02   |  90.0 |
| 01   | 03   |  99.0 |
| 02   | 01   |  70.0 |
| 02   | 02   |  60.0 |
| 02   | 03   |  80.0 |
| 03   | 01   |  80.0 |
| 03   | 02   |  80.0 |
| 03   | 03   |  80.0 |
| 04   | 01   |  50.0 |
| 04   | 02   |  30.0 |
| 04   | 03   |  20.0 |
| 05   | 01   |  76.0 |
| 05   | 02   |  87.0 |
| 06   | 01   |  31.0 |
| 06   | 03   |  34.0 |
| 07   | 02   |  89.0 |
| 07   | 03   |  98.0 |
+------+------+-------+

sid是学生ID，cid是课程ID，分数只是分数。

+-------+---------------+------+-----+---------+-------+
| Field | Type          | Null | Key | Default | Extra |
+-------+---------------+------+-----+---------+-------+
| sid   | varchar(10)   | YES  |     | NULL    |       |
| cid   | varchar(10)   | YES  |     | NULL    |       |
| score | decimal(18,1) | YES  |     | NULL    |       |
+-------+---------------+------+-----+---------+-------+

2.Table学生：

+------+-------+---------------------+------+
| sid  | sname | dob                 | ssex |
+------+-------+---------------------+------+
| 01   | Amy   | 1990-01-01 00:00:00 | M    |
| 02   | Bob   | 1990-12-21 00:00:00 | M    |
| 03   | Cath  | 1990-05-20 00:00:00 | M    |
| 04   | Dick  | 1990-08-06 00:00:00 | M    |
| 05   | Ella  | 1991-12-01 00:00:00 | F    |
| 06   | Geroge| 1992-03-01 00:00:00 | F    |
| 07   | Froth | 1989-07-01 00:00:00 | F    |
| 08   | Hue   | 1990-01-20 00:00:00 | F    |
+------+-------+---------------------+------+

使用

+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| sid   | varchar(10) | YES  |     | NULL    |       |
| sname | varchar(10) | YES  |     | NULL    |       |
| sage  | datetime    | YES  |     | NULL    |       |
| ssex  | varchar(10) | YES  |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+

问题：

返回已注册完全相同课程的学生的sid和sname sid为'01'的学生？

例如，从SC表中，我们可以看到sid'01'的学生注册了课程01,02,03。 sid 02,03,04也注册相同的课程。 因此，我们需要返回

+------+-------+
| sid  | sname |
+------+-------+
| 02   | Bob   |
| 03   | Cath  |
| 04   | Dick  |
+------+-------+

我不知道该怎么做，我不确定是否存在一些优雅的解决方案，例如：

SELECT sid, sname from student
where sid in
( select distinct sid from SC
  group by sid
  having cid = (select distinct cid from SC where sid = '01')
);

有可能这样做吗？

Answer 1

使用此查询：

select sid from sc
group by sid
having 
  sum(cid in (select cid from sc where sid = '01')) = 
  (select count(*) from sc where sid = '01')
  and
  sum(cid not in (select cid from sc where sid = '01')) = 0

您将获得符合您条件的所有学生的ID。
然后将其连接到表student：

select s.sid, s.sname 
from student s inner join (
    select sid from sc
    group by sid
    having 
      sum(cid in (select cid from sc where sid = '01')) = 
      (select count(*) from sc where sid = '01')
      and
      sum(cid not in (select cid from sc where sid = '01')) = 0
) g on g.sid = s.sid
where s.sid <> '01'