Tell me the accreditation level of the hardware model with name Z520e.
select accreditation_level from phone where hardware_model_name = "Z520e"
How about that of Nokia 700?
select accreditation_level from phone where hardware_model_name = "Nokia 700"
Okay, I want to know the accreditation level that more than 3 phones use.
select accreditation_level from phone group by accreditation_level having count(*) > 3