Question: How many students have a food allergy?
Schema: create table has_allergy (allergy varchar, PRIMARY KEY (allergy)); create table allergy_type (allergy varchar, allergytype varchar, PRIMARY KEY (allergy))
SQL: select count(*) from has_allergy as t1 join allergy_type as t2 on t1.allergy = t2.allergy where t2.allergytype = "food"