CREATE TABLE review (a_id NUMBER, u_id NUMBER, i_id NUMBER, rating NUMBER, rank NUMBER)
CREATE TABLE useracct (u_id NUMBER, name CLOB)
CREATE TABLE item (i_id NUMBER, title CLOB)
CREATE TABLE trust (source_u_id NUMBER, target_u_id NUMBER, trust NUMBER)

Find the names of users who did not leave any review.
SELECT name FROM useracct WHERE NOT u_id IN (SELECT u_id FROM review)
SELECT "name" FROM "useracct" WHERE NOT "u_id" IN (SELECT "u_id" FROM "review")