How many phones are on the list?
select count ( * ) from phone
How many different chip models are there?
select count ( * ) from chip_model
How many chip models are not being used in phones with full accreditation?
select model_name from chip_model except select chip_model from phone where accreditation_type = 'Full'
What are the names of the chip models not used in full accreditation phones?
select model_name from chip_model except select chip_model from phone where accreditation_type = 'Full'