Table schema:
CREATE TABLE has_pet (stuid VARCHAR, petid VARCHAR); CREATE TABLE pets (petid VARCHAR, pettype VARCHAR); CREATE TABLE student (stuid VARCHAR)

Question: Find the id of students who do not have a cat pet.
SQL: SELECT stuid FROM student EXCEPT SELECT T1.stuid FROM student AS T1 JOIN has_pet AS T2 ON T1.stuid = T2.stuid JOIN pets AS T3 ON T3.petid = T2.petid WHERE T3.pettype = 'cat'