What are the ids and names of all architects?
select id, name from architect
How many of those architects built less than 3 bridges?
select count(*) from (select t1.id, t1.name from architect as t1 join bridge as t2 on t1.id = t2.architect_id group by t1.id having count(*) < 3)
How many built 3 or more bridges?
select count(*) from (select t1.id, t1.name from architect as t1 join bridge as t2 on t1.id = t2.architect_id group by t1.id having count(*) >= 3)
Please list their ids and names.
select t1.id, t1.name from architect as t1 join bridge as t2 on t1.id = t2.architect_id group by t1.id having count(*) >= 3