how many policy types are there?
select count ( distinct policy_type_code ) from customer_policies
what are those types?
select policy_type_code from customer_policies group by policy_type_code
how about life?
select count ( * ) from customer_policies where policy_type_code = "Life"
what about for each of the last two policies?
select count ( * ), policy_type_code from customer_policies group by policy_type_code having policy_type_code = "Life" or policy_type_code = "Car"
Which of those has the highest count of customers?
select policy_type_code from customer_policies group by policy_type_code order by count ( * ) desc limit 1
And which has least?
select policy_type_code from customer_policies group by policy_type_code order by count ( * ) limit 1
Which policy had the most, again?
select policy_type_code from customer_policies group by policy_type_code order by count ( * ) desc limit 1