Find the number of scientists involved for the projects that require more than 300 hours
select count ( distinct scientist ) from projects as t1 join assignedto as t2 on t1.code = t2.project where t1.hours > 300
Find the number of scientists involved for the projects that require less than 300 hours
select count ( distinct scientist ) from projects as t1 join assignedto as t2 on t1.code = t2.project where t1.hours < 300
and what are the names of the projects requiring more than 300 hours
select name from projects where hours > 300
and what is the scientist id for project Aerodynamics and Bridge Design
select t2.scientist from projects as t1 join assignedto as t2 on t1.code = t2.project where t1.name = 'Aerodynamics and bridge Design'