CREATE TABLE aircraft (aid NUMBER, name VARCHAR2, distance NUMBER)
CREATE TABLE flight (flno NUMBER, origin VARCHAR2, destination VARCHAR2, distance NUMBER, departure_date DATE, arrival_date DATE, price NUMBER, aid NUMBER)
CREATE TABLE certificate (eid NUMBER, aid NUMBER)
CREATE TABLE employee (eid NUMBER, name VARCHAR2, salary NUMBER)

Show how many flights for each origin city with a pie chart.
SELECT origin, COUNT(origin) FROM flight GROUP BY origin
SELECT "origin", COUNT("origin") FROM "flight" GROUP BY "origin"