CREATE TABLE student (stuid VARCHAR, major VARCHAR)
CREATE TABLE member_of_club (clubid VARCHAR, stuid VARCHAR)
CREATE TABLE club (clubname VARCHAR, clubid VARCHAR)

Which club has the most members majoring in '600'?
SELECT t1.clubname FROM club AS t1 JOIN member_of_club AS t2 ON t1.clubid = t2.clubid JOIN student AS t3 ON t2.stuid = t3.stuid WHERE t3.major = "600" GROUP BY t1.clubname ORDER BY COUNT(*) DESC LIMIT 1
SELECT "t1"."clubname" FROM "club" AS "t1" JOIN "member_of_club" AS "t2" ON "t1"."clubid" = "t2"."clubid" JOIN "student" AS "t3" ON "600" = "t3"."major" AND "t2"."stuid" = "t3"."stuid" GROUP BY "t1"."clubname" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 1