22.

查询所有课程的成绩第2名到第3名的学生信息及该课程成绩
**

SELECT
    *
FROM
    Student s
LEFT JOIN
    (SELECT
           a.*,
           (SELECT COUNT(s_score) FROM Score b WHERE a.c_id = b.c_id AND b.s_score > a.s_score)+1 rk
   FROM 
           Score a
   ORDER BY c_id, s_score DESC) t
ON 
    s.s_id = t.s_id
WHERE t.rk IN (2, 3)