List the name of the company that produces more than one phone model.
select company_name from phone group by company_name having count ( * ) > 1
Hmmm. Please list the name of the company that produces only one phone model.
select company_name from phone group by company_name having count ( * ) = 1
Ok. Can you show me the models produced by Nokia Corporation?
select hardware_model_name from phone where company_name = "Nokia Corporation"