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

Show me the proportion of the number of flights by 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"