-- John Smith가 일하는 project number를 검색하라 select w.pno from employee e, works_on w where e.fname='John' and e.lname='Smith' and e.ssn = w.essn; -- John Smith가 일하는 project 를 수행하는 사람들의fname, lname 를 검색하라. Hint: 중첩, IN select distinct e.fname, e.lname from employee e, works_on w where w.pno IN ( select w.pno from employee e, works_on w where e.fname='John' and e.lname='Smith' and e.ssn = w.essn) and ..