1.	SELECT S.fname, S.lname,S.age,S.sex
	FROM Student S, Lives_in L
	WHERE L.stuid=S.stuid AND NOT  EXISTS
                                (SELECT S2.stuid
                                FROM Student S2,Lives_in L2
                                WHERE L2.stuid=S2.stuid
                                        AND S2.stuid<>S.stuid
                                        AND L2.dormid=L.dormid
                                        AND L2.room_number=L.room_number);

2.	SELECT  P.fname, P.lname, P.sex
        	FROM   ((SELECT  S.fname, S.lname, S.sex
                FROM   Student S, Enrolled_in E, Course C, Department D
                WHERE  S.stuid=E.stuid AND C.cid=E.cid
                       AND C.dno=D.dno AND D.dname= 'Computer Science' )
		 UNION
                (SELECT F.fname, F.lname, F.sex
                FROM    Faculty F, Course R, Department T
                WHERE   R.instructor=F.facid
                        AND R.dno=T.dno AND T.dname='Computer Science' )) P;


3.	SELECT DISTINCT S.fname, S.lname, S.sex, S.major
 	 FROM Student S
 	 WHERE S.stuid = (SELECT L.wholikes
                   FROM Likes L
                   GROUP BY L.wholikes
                   HAVING count(L.whoisliked) = (SELECT count(stuid)
                                                 FROM Student));

4.	SELECT S.fname, S.lname, S.age, S.major, sum(C.credits) as numbercredits
     	 FROM Student S, Enrolled_in E, Course C
   	 WHERE S.stuid = E.stuid and C.cid = E.cid
    	GROUP BY S.fname, S.lname, S.major, S.age;

5.	SELECT S.fname, S.lname, S.major
  	 FROM Student S, Enrolled_in E, Course C
   	WHERE S.stuid = E.stuid AND C.cid = E.cid
   	GROUP BY S.fname, S.lname, S.major
   	HAVING sum(C.credits) > 20;


6.	SELECT  distinct f.fname||' '||f.lname Faculty_Name
  	FROM Student s1, Student s2, Faculty f, Enrolled_in ei
 	WHERE s1.advisor = f.facid
    	AND s1.stuid = ei.stuid
      	AND s2.stuid IN (
                       SELECT stuid
                       FROM Enrolled_in
                       WHERE cid = ei.cid
                         AND stuid != s1.stuid
                     )
     	AND s2.stuid IN (
                      SELECT l1.stuid
                      FROM lives_in l1, lives_in l2,
                           Student s, Minor_in mi, member_of mo
                      WHERE l1.stuid < l2.stuid
                        AND l1.dormid = l2.dormid
                        AND l1.room_number = l2.room_number
                        AND s.stuid = l2.stuid
                        AND mi.stuid = l2.stuid
                        AND ( s.major IN (
                                           SELECT dno
                                           FROM member_of
                                           WHERE facid = f.facid
                                          )
                              or
                              mi.dno IN  (
                                           SELECT dno
                                           FROM member_of
                                           WHERE facid = f.facid
                                         )
                            )
                     );

7.	SELECT temp1.fname,temp1.lname
 	 FROM
       	 (
       	     SELECT s1.fname,s1.lname,s1.major,COUNT(s2.stuid) ans
            FROM student s1,student s2
            WHERE (s1.stuid,s2.stuid)
            IN
                (
                        SELECT wholikes,whoisliked
                        FROM likes
                )
                and s1.major = s2.major and s1.stuid <> s2.stuid
            GROUP BY s1.stuid,s1.fname,s1.lname,s1.major
        )temp1,
        (
                SELECT s3.major,COUNT(s3.stuid) ans
                FROM student s3
                GROUP BY s3.major
        )temp2
 	 WHERE temp1.major=temp2.major and temp1.ans=temp2.ans-1;



8.	SELECT dname,total
  	FROM department d,
                (
                 SELECT dep,SUM(cnt) total
                 FROM
                 (
                        SELECT c.dno dep,(k.ans * c.credits) cnt
                        FROM course c,
                        (
                                SELECT cid,COUNT(stuid) ans
                                FROM enrolled_in GROUP BY cid
                        )k
                        WHERE c.cid = k.cid
                )GROUP BY dep
	)res WHERE d.dno=res.dep;



9.	SELECT R.fname, R.lname, R.age
	FROM Student R
	WHERE R.stuid NOT IN ( SELECT S.stuid
                       FROM  Student S, Student T
                       WHERE S.age<T.age AND S.major=T.major);


10.
    select EI.CID,CName,BelowB,EnrolledCount,
           BOrBelow*1.0/EnrolledCount*100 as PercentBOrBelow,
           Fname,Lname
    from (select CID,count(if(gradepoint < 3,1,NULL)) BelowB,
                     count(if(gradepoint <= 3,1,NULL)) BOrBelow,
                     count(*) EnrolledCount
          from (select CID,CourseGrades.Grade,gradepoint
                from (select CID,Grade from Enrolled_in) as CourseGrades
                join Gradeconversion GC
                on CourseGrades.Grade=GC.lettergrade) as G
          group by CID) EI,Course C,Faculty F
    where EI.CID=C.CID and C.Instructor=F.FacID;


11.	SELECT s1.stuid, s1.fname , s1.lname , s2.stuid, s2.fname , s2.lname
 	  FROM student s1 , student s2
 	  WHERE (s1.stuid,s2.stuid)
 	  IN
      	  (
                SELECT a.wholoves,a.whoisloved
                FROM loves a,loves b
                WHERE a.wholoves=b.whoisloved and a.whoisloved=b.wholoves and a.wholoves 	!= a.whoisloved and a.wholoves < a.whoisloved );



12.	SELECT S1.fname, S1.lname, S1.sex, S2.fname, S2.lname, S2.sex
	FROM   Student S1, Student S2, Loves L1, Loves L2, Lives_in V1,Lives_in V2
	WHERE  L1.wholoves=S1.stuid AND L1.whoisloved=S2.stuid
   	    AND L2.wholoves=S2.stuid AND L2.whoisloved=S1.stuid
    	   AND S1.stuid<S2.stuid
     	  AND V1.stuid=S1.stuid AND V2.stuid=S2.stuid
     	  AND V1.dormid=V2.dormid
    	    AND V1.room_number=V2.room_number;

13.	SELECT S1.fname, S1.lname
	FROM Student S1
	WHERE S1.stuid IN
                           (SELECT L1.wholoves
                                FROM Loves L1
                                WHERE NOT EXISTS
	 (SELECT *FROM Loves L2
           WHERE L2.wholoves=L1.whoisloved AND L2.whoisloved=L1.wholoves));


14.	

    SELECT S3.Fname as LoverFname, S3.Lname as LoverLname,
           S1.Fname as Roomie1Fname, S1.Lname as Roomie1Lname,
           S2.Fname as Roomie2Fname, S2.Lname as Roomie2Lname
    FROM (select *
          from (select distinct L1.StuID Roomie1,L2.StuID Roomie2
                from Lives_in L1,Lives_in L2
                where L1.dormid=L2.dormid
                      and L1.room_number=L2.room_number
                      and L1.StuID < L2.StuID) as Roomies
          join (select Lov1.WhoLoves,Lov1.WhoIsLoved Love1,Lov2.WhoIsLoved Love2
                from Loves as Lov1,Loves as Lov2
                where Lov1.WhoLoves=Lov2.WhoLoves
                      and Lov1.WhoIsLoved < Lov2.WhoIsLoved) as LovePairs
          on Roomies.Roomie1=LovePairs.Love1
             and Roomies.Roomie2=LovePairs.Love2) as ThirdPartyLove,
        Student S1,Student S2,Student S3
    WHERE S1.StuID=Roomie1 and S2.StuID=Roomie2 and S3.StuID=WhoLoves;
    

15.    SELECT T4.fname,T4.lname,T4.advisor,T4.credits
        FROM
        (SELECT S1.major AS major, AVG(T1.credits) AS avgcredits
        FROM (SELECT E1.stuid AS stuid, SUM (C1.credits) AS credits
        FROM Enrolled_in E1,Course C1
        WHERE E1.Cid=C1.cid
        GROUP BY E1.stuid)T1,
        Student S1
        WHERE S1.stuid=T1.stuid
        GROUP BY S1.major) T3,
        (SELECT S2.stuid As stuid,
        S2.lname As lname,
        S2.fname AS fname,
        S2.advisor AS advisor,
        S2.major AS major,
        T2.credits AS credits
        FROM (SELECT E1.stuid AS stuid, SUM (C1.credits) AS credits
        FROM Enrolled_in E1,Course C1
        WHERE E1.Cid=C1.cid
        GROUP BY E1.stuid)T2,
        Student S2
        WHERE S2.stuid=T2.stuid)T4
        WHERE T3.major=T4.major AND T4.credits>T3.avgcredits;
OR
    select StuID,Student,Advisor,AdvName,CreditsEnrolled,SInfo.Major,AvgCreditsEnrolled
    from (select S.StuID,concat(S.Fname," ",S.Lname) as Student,Major,
                 Advisor,concat(F.Fname," ",F.Lname) as AdvName,
                 sum(Credits) as CreditsEnrolled
          from Enrolled_in E,Course C,Student S,Faculty F
          where E.StuID=S.StuID and E.CID=C.CID and S.Advisor=F.FacID
          group by StuID) as SInfo
    join (select Major,avg(CreditsEnrolled) AvgCreditsEnrolled
          from (select Major,sum(Credits) as CreditsEnrolled
                from Enrolled_in E,Course C,Student S,Faculty F
                where E.StuID=S.StuID and E.CID=C.CID and S.Advisor=F.FacID
                group by S.StuID) as CredByMajor
          group by Major) as AvgCredits
    on SInfo.Major=AvgCredits.Major
    where CreditsEnrolled > AvgCreditsEnrolled;
    



16.    SELECT S.fname,S.lname
        FROM Student S
        WHERE S.stuid IN
       (SELECT T1.stuid
        FROM
        (SELECT L1.whoisliked AS stuid,COUNT (*) AS likednum
        FROM Likes L1
        GROUP BY L1.whoisliked)T1
        WHERE T1.likednum=(SELECT MAX (T2.likednum)
        FROM (SELECT L1.whoisliked AS stuid,COUNT (*) AS likednum
                                                        FROM Likes L1
                GROUP BY L1.whoisliked)T2));

    OR
      select WhoIsLiked,concat(Fname," ",Lname) Name,HowManyLikeThem
      from (select *
            from (select WhoIsLiked,count(*) HowManyLikeThem
                  from Likes
                  group by WhoIsLiked) as Likable
            where HowManyLikeThem in (select max(HowManyLikeThem) mHM
                                      from (select WhoIsLiked,count(*) HowManyLikeThem
                                            from Likes
                                            group by WhoIsLiked) as Likable
                                      )
            ) as MaxLiked,Student S
      where MaxLiked.WhoIsLiked=S.StuID;
      


17.	SELECT S2.fname,S2.lname,T2.likedorlovednum AS likedorlovednum
	FROM
	(SELECT S1.stuid AS stuid,S1.stuid-S1.stuid AS likedorlovednum
	FROM Student S1
	WHERE (NOT EXISTS (SELECT *
                                        FROM Likes LI1
                                        WHERE LI1.whoisliked=S1.stuid))
                AND
                (NOT EXISTS (SELECT *FROM Loves LO1 WHERE LO1.whoisloved=S1.stuid))
	UNION
	SELECT T1.whoislikedorloved AS stuid,COUNT(*) AS likedorlovednum
	FROM
	(SELECT LI2.wholikes AS wholikesorloves, LI2.whoisliked AS whoislikedorloved
	FROM Likes LI2
	UNION
	SELECT LO2.wholoves AS wholikesorloves,LO2.whoisloved AS whoislikedorloved
	FROM Loves LO2)T1
	GROUP BY T1.whoislikedorloved) T2,
	Student S2
	WHERE S2.stuid=T2.stuid
	ORDER BY likedorlovednum DESC;

18.	SELECT S1.fname,S1.lname,S1.age
	FROM Student S1
	WHERE S1.age>(SELECT AVG(S2.age)
         FROM Student S2);

19.
SELECT d.division, Sum(Enrollment.result)
FROM Department d,
        (SELECT c.dno AS department, COUNT(e.stuid) AS result
        FROM Course c, Enrolled_in e WHERE c.cid = e.cid GROUP BY(c.dno)) AS Enrollment
WHERE (d.dno = Enrollment.department) GROUP BY (d.division);

20.
SELECT result2.fname,Max(result2.count)
FROM
        (SELECT result.fname AS fname, COUNT(result.fname) AS count FROM
                (SELECT * FROM Faculty UNION SELECT * FROM Student) AS result
        GROUP BY (result.fname) ORDER BY count DESC) AS result2;

21.
SELECT d.dname, result.department, MIN(result.count) FROM Department d,
        (SELECT c.dno AS department,COUNT(e.stuid) AS count
        FROM Course c, Enrolled_in e WHERE c.cid = e.cid GROUP BY(c.dno)) AS result
WHERE result.department = d.dno GROUP BY result.count ASC LIMIT 1;

22.
SELECT student1.fname,student1.lname,student1.stuid,student2.fname,student2.lname,student2.stuid FROM Student student1, Student student2,
        (SELECT DISTINCT s.stuid AS stu1, s2.stuid AS stu2 FROM
                (SELECT DISTINCT p.stuid,p.gameid,e.cid FROM Plays_Games p, Enrolled_in e WHERE (e.cid IN (SELECT cid FROM Course WHERE instructor = (SELECT facid FROM Faculty WHERE fname = 'Yair' AND lname = 'Amir')))
                        AND (e.stuid = p.stuid)) AS s,
                (SELECT DISTINCT p.stuid,p.gameid,e.cid FROM Plays_Games p, Enrolled_in e WHERE (e.cid IN (SELECT cid FROM Course WHERE instructor = (SELECT facid FROM Faculty WHERE fname = 'Yair' AND lname = 'Amir')))
                        AND (e.stuid = p.stuid)) AS s2
        WHERE s.cid <> s2.cid AND s.cid < s2.cid AND s.stuid NOT IN (SELECT stuid FROM Plays_Games WHERE gameid IN (SELECT gameid FROM Plays_Games where stuid = s2.stuid))
    ) AS result
WHERE result.stu1 = student1.stuid AND result.stu2 = student2.stuid;

23.
SELECT s.fname,s.lname,s.stuid,sportsgpa.gpa + 0.1 AS GPA FROM Student s,
(
        SELECT forgpa2.stuid,TRUNCATE(forgpa2.points/forgpa2.credits,2) as gpa FROM
                (SELECT SUM(forgpa.gradepoint * forgpa.credits) AS points, SUM(forgpa.credits) AS credits, forgpa.stuid AS stuid FROM
                        (SELECT g.gradepoint,e.grade,c.credits,e.stuid,e.cid FROM Course c,Gradeconversion g, Enrolled_in e
                        WHERE e.stuid IN (SELECT stuid FROM Student) AND(e.grade = g.lettergrade)AND(c.cid = e.cid))
                AS forgpa GROUP BY(stuid)) AS forgpa2
    ) AS sportsgpa
WHERE sportsgpa.stuid IN (SELECT stuid FROM SportsInfo) AND s.stuid = sportsgpa.stuid
UNION
SELECT s.fname,s.lname,s.stuid,sportsgpa.gpa AS GPA FROM Student s,
        (SELECT forgpa2.stuid,TRUNCATE(forgpa2.points/forgpa2.credits,2) as gpa FROM
                (SELECT SUM(forgpa.gradepoint * forgpa.credits) AS points, SUM(forgpa.credits) AS credits, forgpa.stuid AS stuid FROM
                        (SELECT g.gradepoint,e.grade,c.credits,e.stuid,e.cid FROM Course c,Gradeconversion g, Enrolled_in e
                        WHERE e.stuid IN (SELECT stuid FROM Student) AND(e.grade = g.lettergrade)AND(c.cid = e.cid))
                AS forgpa GROUP BY(stuid)) AS forgpa2)
        AS sportsgpa
WHERE sportsgpa.stuid NOT IN (SELECT stuid FROM SportsInfo) AND s.stuid = sportsgpa.stuid
;

24.
SELECT s.stuid,s.fname,s.lname, COUNT(e.cid) FROM Enrolled_in e, Student s
        WHERE e.stuid IN (SELECT stuid FROM Has_Allergy
                WHERE allergy IN (SELECT allergy FROM Allergy_Type WHERE allergytype = 'FOOD'))
        AND e.stuid = s.stuid
    GROUP BY e.stuid HAVING COUNT(e.cid)>3;

25.
SELECT sports.sportname,TRUNCATE(SUM(sportsgpa.sportgpa)/COUNT(sports.stuid),2) AS AverageGPA FROM
    (SELECT forgpa2.stuid,TRUNCATE(forgpa2.points/forgpa2.credits,2) as sportgpa FROM
                (SELECT SUM(forgpa.gradepoint * forgpa.credits) AS points, SUM(forgpa.credits) AS credits, forgpa.stuid AS stuid FROM
                        (SELECT g.gradepoint,e.grade,c.credits,e.stuid,e.cid FROM Course c,Gradeconversion g, Enrolled_in e
                        WHERE e.stuid IN (SELECT stuid FROM Student) AND(e.grade = g.lettergrade)AND(c.cid = e.cid))
                AS forgpa GROUP BY(stuid)) AS forgpa2) AS sportsgpa, SportsInfo sports WHERE sports.stuid = sportsgpa.stuid
        GROUP BY (sports.sportname);

26.
SELECT *
        FROM ((SELECT SI.SportName, sum(SI.HoursPerWeek) as sum_hours
               FROM SportsInfo as SI
               GROUP BY SI.SportName
               HAVING sum(SI.HoursPerWeek) >= all (SELECT sum(HoursPerWeek)
                                                   FROM SportsInfo
                                                   GROUP BY SportName))
               UNION

              (SELECT SI.SportName, sum(SI.HoursPerWeek) as sum_hours
               FROM SportsInfo as SI
               GROUP BY SI.SportName
               HAVING sum(SI.HoursPerWeek) <= all (SELECT sum(HoursPerWeek)
                                                   FROM SportsInfo
                                                   GROUP BY SportName)))A;
                                                   
27.
 SELECT Scholarship-NoScholarship
	FROM (SELECT AVG(GamesPlayed) NoScholarship
		FROM SportsInfo
		WHERE OnScholarship = "N") NoScholar,
		(SELECT AVG(GamesPlayed) Scholarship
		FROM SportsInfo
		WHERE OnScholarship = "Y") Scholar;


28.
select Department.DName
	   , COUNT(a.StuID) as num
	   , AVG(a.GPA) as GPA
from (
select Student.StuID
	   , Student.Major
	   , AVG(Gradeconversion.gradepoint) as GPA
from Student
	 , SportsInfo
	 , Enrolled_in
	 , Gradeconversion
where Student.StuID = SportsInfo.StuID
	  and Student.StuID = Enrolled_in.StuID
	  and Enrolled_in.Grade = Gradeconversion.lettergrade
group by Student.StuID, Student.Major) a
	, Department
where a.Major = Department.DNO
group by Department.DName;

29.
SELECT Early_riser_athletes.num / Early_risers.num * 100 AS percentage
FROM (SELECT count(DISTINCT S.stuid) AS num
    FROM Student S, Preferences P
    WHERE S.stuid = P.stuid
        AND P.sleephabits = "EarlyRiser"
        AND S.stuid IN (SELECT stuid
            FROM SportsInfo SI
            GROUP BY SI.stuid))
   AS Early_riser_athletes,
   (SELECT count(DISTINCT S.stuid) AS num
    FROM Student S, Preferences P
    WHERE S.stuid = P.stuid
        AND P.sleephabits = "EarlyRiser")
   AS Early_risers;
                 
 
30.
SELECT D.dormid, D.dorm_name, D.Gender, count(distinct(H.amenid)) as num_amenities
        FROM SportsInfo as S, Dorm as D, Lives_in as L, Has_amenity as H
        WHERE S.StuID = L.StuID and L.dormid = D.dormid and D.dormid = H.dormid
        GROUP BY D.dormid
        HAVING count(distinct(S.StuID)) >= all (SELECT count(distinct(S.StuID))
                                                FROM SportsInfo as S, Dorm as D, Lives_in as L
                                                WHERE S.StuID = L.StuID and L.dormid = D.dormid
                                                GROUP BY D.dormid);
                                                
31.
SELECT COUNT(Student.StuID) as NumWomen
	FROM Student
	WHERE StuID in (SELECT StuID
			FROM SportsInfo
			WHERE SportName = "Basketball"
			or SportName = "Tennis")
	and Sex = "F"
	and StuID in (SELECT StuID 
			FROM Preferences
			WHERE MusicType = "StudiesWith");
			
32.
SELECT D.Dname, count(distinct(S.StuID)) as count
        FROM Department as D, Student as S, Preferences as P, Has_Allergy as H
        WHERE D.DNO = S.Major and S.StuID = P.StuID and S.StuID = H.StuID 
              and P.Smoking = 'Yes' and S.StuID not in (SELECT StuID 
                                                        FROM SportsInfo)
														GROUP BY D.Dname;

33.
select Student.Fname
	   , Student.LName
	   , SUM(t.timecost) as timecost
from 
(
select Enrolled_in.StuID as StuID
	   , COUNT(Enrolled_in.CID)*10 as timecost
from Enrolled_in
group by Enrolled_in.StuID

union all

select SportsInfo.StuID as StuID
	   , SUM(SportsInfo.HoursPerWeek) as timecost
from SportsInfo
group by SportsInfo.StuID
) t, Student
where t.StuID = Student.StuID
group by t.StuID
order by SUM(t.timecost) DESC
limit 1

34.
select Student.Fname
	   , Student.LName
from (
select Likes.WhoIsLiked as StuID
	   , COUNT(Likes.WhoLikes) as num
from Likes
group by Likes.WhoIsLiked
order by COUNT(Likes.WhoLikes) DESC
limit 1) t, Student
where t.StuID = Student.StuID

35.
SELECT DISTINCT CName
	FROM Course, (SELECT CID, COUNT(StuID) NumStudents
			FROM Enrolled_in
			WHERE StuID in (SELECT StuID
					FROM Plays_Games
					GROUP BY StuID
					HAVING SUM(Hours_Played) >= 50)
			GROUP BY CID) StudentGamers
	WHERE StudentGamers.CID = Course.CID
	ORDER BY NumStudents DESC;
	
36.
SELECT DISTINCT dorm_name
	FROM Dorm, (SELECT stuid, dormid
			FROM Lives_in
			WHERE stuid in (SELECT StuID
				FROM Plays_Games
				WHERE GameID in (SELECT GameID
						FROM Video_Games
						WHERE GName != "Europe is the Universe"))) Gamers
	WHERE Dorm.dormid = Gamers.dormid;

37.
SELECT SUM(GameHours)
FROM Student S, Preferences P, (SELECT StuID, SUM(Hours_Played) GameHours
						FROM Plays_Games
						GROUP BY StuID) Gamers
WHERE S.StuID = Gamers.StuID
and S.StuID = P.StuID
and P.Smoking = "no"
and S.StuID in (SELECT WhoLikes
		FROM Likes);

38.
SELECT fname, lname
FROM Student
WHERE EXISTS (
	SELECT *
	FROM Enrolled_in, Course, Department, Gradeconversion
	WHERE Student.stuid=Enrolled_in.stuid AND Enrolled_in.grade=Gradeconversion.lettergrade
	AND Gradeconversion.gradepoint>=4.0 AND Enrolled_in.cid=Course.cid
	AND Course.dno=Department.dno AND Department.dname='Computer Science') AND NOT EXISTS (
	SELECT *
	FROM Plays_Games
	WHERE Plays_Games.stuid=Student.stuid);
	
39.
SELECT AVG(S1. Hours_Played) FROM
   (SELECT P.Hours_Played, L.dormid
    FROM Student as St, Plays_Games as P, Lives_in as L
    WHERE St.StuID NOT IN (SELECT StuID FROM Participates_in)
    AND St.StuID = P.StuID AND St.StuID = L.StuID) AS S1,
   (SELECT P.Hours_Played, L.dormid
    FROM Student as St, Plays_Games as P, Lives_in as L
    WHERE St.StuID NOT IN (SELECT StuID FROM Participates_in)
    AND St.StuID = P.StuID AND St.StuID = L.StuID) AS S2
WHERE S1.dormid != S2.dormid;

40.
select a.StuID
	   , b.StuID
	   , c.StuID
from Student a
	 , Student b
	 , Student c
where exists(select * from Loves where a.StuID = Loves.WhoLoves and b.StuID = Loves.WhoIsLoved)
      and exists(select * from Loves where b.StuID = Loves.WhoLoves and c.StuID = Loves.WhoIsLoved)
      and exists(select * from Loves where c.StuID = Loves.WhoLoves and a.StuID = Loves.WhoIsLoved)
      and not exists (select * from Loves where b.StuID = Loves.WhoLoves and a.StuID = Loves.WhoIsLoved)
      and not exists (select * from Loves where c.StuID = Loves.WhoLoves and b.StuID = Loves.WhoIsLoved)
      and not exists (select * from Loves where a.StuID = Loves.WhoLoves and c.StuID = Loves.WhoIsLoved)
      and a.StuID < b.StuID
      and b.StuID < c.StuID