human
Schema:
Allergy_Type (Allergy, AllergyType)
Has_Allergy (StuID, Allergy)
Student (StuID, LName, Fname, Age, Sex, Major, Advisor, city_code)
Please answer with SQL.
assistant
Sure, I understand.
human
What are all the student ids?
assistant
SELECT StuID FROM Student;
human
Of these, which students ids correspond to students without allergies?
assistant
SELECT StuID FROM Student EXCEPT SELECT StuID FROM Has_allergy ;