How many membership registrations are there in file?
select count(*) from membership_register_branch
How many of those were registered after 2015?
select count(*) from membership_register_branch where register_year > 2015
What about for each branch?
select branch_id, count(*) from membership_register_branch where register_year > 2015 group by branch_id
Show me the name for each branch instead of id.
select t2.name, count(*) from membership_register_branch as t1 join branch as t2 on t1.branch_id = t2.branch_id where t1.register_year > 2015 group by t2.branch_id