SQL查询返回子查询的确切列表

Question

So I am given this question:

Consider the following tables where keys are bolded: Professor( profid , profname, department) Student( studid , studname, major), and Advise( profid , studid ).

Return the names of the students who have exactly the same advisors as student whose id is '123456789'.

The query that I came up with doesn't return the exact same advisors, but rather the advisors that are common between student 123456789 and other students. An example is if student 123456789 has advisors 1 and 2, and student 5 only has advisor 1, my current query will return student 5, which is incorrect. The query is only supposed to return students that have both advisors 1 and 2. Here is my query so far:

SELECT studname
FROM Student
WHERE studid IN 
(
    SELECT DISTINCT studid
    FROM Advise
    WHERE profid IN
    (
        SELECT profid
        FROM Advise
        WHERE studid = '123456789'
    )
);

How can I get this query to return the exact list of students that advise student 123456789?

Answer 1

I test it run right. You can try:

SELECT a.studid, b.studname
FROM (
    SELECT studid, COUNT(studid) AS numstud
    FROM Advise 
    WHERE 
        profid IN (
            SELECT profid FROM Advise WHERE studid = 123456789
        ) AND 
        studid NOT IN (
            SELECT studid FROM Advise WHERE profid NOT IN (
                SELECT profid FROM Advise WHERE studid = 123456789
            )
        )
    GROUP BY studid
    HAVING numstud = (SELECT COUNT(*) FROM Advise WHERE studid = 123456789)
) AS a LEFT JOIN Student AS b ON (a.studid = b.studid)

Answer 2

My solution is finding student not same advisors , then take negative of this.

Please try with script:

   SELECT studid,studname
FROM Student
WHERE studid  not in
(
   select studid
   from
   (
    SELECT a.studid, b.profid
    FROM Advise a
    left join
    (
        SELECT profid
        FROM Advise
        WHERE studid = '123456789'
    ) b on b.profid = a.profid
    where a.studid not like '123456789'
    ) x
    where x.profid is null
)
group by studid,studname
having count(*) = (SELECT count(profid) FROM Advise WHERE studid = '123456789')

Answer 3

Are you looking for some thing this?

select studname from Student where studid in 
(
  select studid from ( 
     select studid, GROUP_CONCAT(profid) profs from  advice 
     group by studid having profs in ( 
          select studid, GROUP_CONCAT(profid) profs from  advice group by 
          studid having studid = '123456789' 
     )
  ) 
)