Which bridges have a length above 80 meters?
select * from bridge where length_meters > 80
Show all the architects that have built each of these bridges.
select * from architect as t2 join bridge as t3 on t3.architect_id = t2.id where t3.length_meters > 80
What are the distinct name of the mills built by these architects?
select distinct t1.name from mill as t1 join architect as t2 on t1.architect_id = t2.id join bridge as t3 on t3.architect_id = t2.id where t3.length_meters > 80