Which state has the most employees?
select t1.state_province_county from addresses as t1 join employees as t2 on t1.address_id = t2.employee_address_id group by t1.state_province_county order by count ( * ) desc limit 1
Which state has the least?
select t1.state_province_county from addresses as t1 join employees as t2 on t1.address_id = t2.employee_address_id group by t1.state_province_county order by count ( * ) limit 1
WHich states have no employees?
select state_province_county from addresses where address_id not in ( select employee_address_id from employees )