CREATE TABLE participates_in (stuid DECIMAL, actid DECIMAL)
CREATE TABLE activity (actid DECIMAL, activity_name TEXT)
CREATE TABLE faculty (facid DECIMAL, lname TEXT, fname TEXT, rank TEXT, sex TEXT, phone DECIMAL, room TEXT, building TEXT)
CREATE TABLE student (stuid DECIMAL, lname TEXT, fname TEXT, age DECIMAL, sex TEXT, major DECIMAL, advisor DECIMAL, city_code TEXT)
CREATE TABLE faculty_participates_in (facid DECIMAL, actid DECIMAL)

Show the ids of the students who don't participate in any activity.
SELECT stuid FROM student EXCEPT SELECT stuid FROM participates_in
SELECT "stuid" FROM "student" EXCEPT SELECT "stuid" FROM "participates_in"