Sql 选择“使用联接表从一个父表获取值”“从另一个父表获取给定值”

我有一个DB，它有两个父表，它们由连接表中的外键引用，我绞尽脑汁想弄清楚，如果给定一个父表中的值，如何从一个父表中获取所有相关行。例如，使用以下表格和列：

以及如下所示的行：

schoolA:
1, MATH, 101
2, SOCI, 100
3, HIST, 211

schoolB:
1, MATH, 100
2, MATH, 110
3, ENGL, 210

schoolB_equivalencies:
1, 1, 1 (school A's MATH 101 equivalent to school B's MATH 100)
2, 1, 2 (school A's MATH 101 equivalent to school B's MATH 110)

给定schoolA课程前缀和编号（比如数学101），我如何构造SELECT查询以查找schoolB_等价表中列出的所有schoolB课程前缀/编号对？例如，我的数学101虚拟课程，我将如何获得

MATH 100
MATH 110

---

此查询获取有关原始课程的信息：

SELECT *
FROM schoolA
WHERE course_prefix = 'MATH'
  AND course_number = 101;

---

此查询获取有关联接表中相应行的信息：

SELECT *
FROM schoolB_ueqivalencies
WHERE schoolA_id = (SELECT id
                    FROM schoolA
                    WHERE course_prefix = 'MATH'
                      AND course_number = 101);

此查询获取schoolB中相应行的信息：

SELECT *
FROM schoolB_ueqivalencies
WHERE schoolA_id = (SELECT id
                    FROM schoolA
                    WHERE course_prefix = 'MATH'
                      AND course_number = 101);

SELECT *
FROM schoolB
WHERE id IN (SELECT schoolB_id
             FROM schoolB_ueqivalencies
             WHERE schoolA_id = (SELECT id
                                 FROM schoolA
                                 WHERE course_prefix = 'MATH'
                                   AND course_number = 101));