What are the first and last name of all the students?
select fname, lname from student
Of them, who are allergic to any type of food?
select distinct t3.fname, t3.lname from has_allergy as t1 join allergy_type as t2 on t1.allergy = t2.allergy join student as t3 on t1.stuid = t3.stuid where t2.allergytype = "food"
And who are not?
select fname, lname from student where stuid not in (select t1.stuid from has_allergy as t1 join allergy_type as t2 on t1.allergy = t2.allergy where t2.allergytype = "food")