-- Database schema
| Scientists : SSN [ INT ] primary_key , Name [ TEXT ] | Projects : Code [ TEXT ] primary_key , Name [ TEXT ] , Hours [ INT ] | AssignedTo : Scientist [ INT ] primary_key AssignedTo.Scientist = Scientists.SSN , Project [ TEXT ] AssignedTo.Project = Projects.Code |
-- -- Find the name of the scientist who worked on both a project named 'Matter of Time' and a project named 'A Puzzling Parallax'.

SELECT T3.name FROM assignedto AS T1 JOIN projects AS T2 ON T1.project  =  T2.code JOIN scientists AS T3 ON T1.scientist  =  T3.SSN WHERE T2.name  =  'Matter of Time' INTERSECT SELECT T3.name FROM assignedto AS T1 JOIN projects AS T2 ON T1.project  =  T2.code JOIN scientists AS T3 ON T1.scientist  =  T3.SSN WHERE T2.name  =  'A Puzzling Parallax';