CREATE TABLE chip_model (model_name VARCHAR(255), chip_model VARCHAR(255), Accreditation_type VARCHAR(255)); CREATE TABLE phone (model_name VARCHAR(255), chip_model VARCHAR(255), Accreditation_type VARCHAR(255))
Find the names of the chip models that are not used by any phone with full accreditation type.
    
SQL: SELECT model_name FROM chip_model EXCEPT SELECT chip_model FROM phone WHERE Accreditation_type = 'Full'