CREATE TABLE projects (code TEXT, name TEXT, hours DECIMAL)
CREATE TABLE scientists (ssn DECIMAL, name TEXT)
CREATE TABLE assignedto (scientist DECIMAL, project TEXT)

Find the number of scientists who are not assigned to any project.
SELECT COUNT(*) FROM scientists WHERE NOT ssn IN (SELECT scientist FROM assignedto)
SELECT COUNT(*) FROM "scientists" WHERE NOT "ssn" IN (SELECT "scientist" FROM "assignedto")