CREATE TABLE review (a_id NUMBER, u_id NUMBER, i_id NUMBER, rating NUMBER, rank NUMBER)
CREATE TABLE item (i_id NUMBER, title VARCHAR2)
CREATE TABLE trust (source_u_id NUMBER, target_u_id NUMBER, trust NUMBER)
CREATE TABLE useracct (u_id NUMBER, name VARCHAR2)

For each user, find their name and the number of reviews written by them. Plot them as pie chart.
SELECT name, COUNT(*) FROM useracct AS T1 JOIN review AS T2 ON T1.u_id = T2.u_id GROUP BY T2.u_id
SELECT "name", COUNT(*) FROM "useracct" "T1" JOIN "review" "T2" ON "T1"."u_id" = "T2"."u_id" GROUP BY "T2"."u_id"