CREATE TABLE projects (code CLOB, name CLOB, hours NUMBER)
CREATE TABLE scientists (ssn NUMBER, name CLOB)
CREATE TABLE assignedto (scientist NUMBER, project CLOB)

What are the names of scientists who have not been assigned a project?
SELECT name FROM scientists WHERE NOT ssn IN (SELECT scientist FROM assignedto)
SELECT "name" FROM "scientists" WHERE NOT "ssn" IN (SELECT "scientist" FROM "assignedto")