如何从MySQL表中获取多列具有相同值的所有行？

Question

我有一个表学生，其列有rollNumber，majorSubject，minorSubject，fullName。

现在给出一个rollNumber如何查找具有相同majorSubject的所有学生，minorSubject作为具有给定rollNumber的学生。

我想出了什么：

SELECT * FROM students WHERE
majorSubject IN (SELECT majorSubject FROM students WHERE rollNumber='<rollNumber>') AND
minorSubject IN (SELECT minorSubject FROM students WHERE rollNumber='<rollNumber>')

正如您所看到的，我正在运行相同的子查询两次。我相信应该有一个优化或更好的方法。

Answer 1

SELECT allSt.* 
FROM students allSt
join students st 
-- check the same majorSubject AND the same minorSubject --
on allSt.majorSubject = st.majorSubject and allSt.minorSubject = st.minorSubject 
WHERE
st.rollNumber = '<rollNumber>' AND
-- exclude student with the given rollNumber from the result set --
allSt.rollNumber <> '<rollNumber>'