-- 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 |
-- -- How many different scientists are assigned to any project?

SELECT count(DISTINCT scientist) FROM assignedto;