CREATE TABLE PersonFriend (name VARCHAR2, friend VARCHAR2, year NUMBER)
CREATE TABLE Person (name VARCHAR2, age NUMBER, city CLOB, gender CLOB, job CLOB)

A bar chart about what is average age for different job title?, and rank by the the average of age in desc.
SELECT job, AVG(age) FROM Person GROUP BY job ORDER BY AVG(age) DESC
SELECT "job", AVG("age") FROM "Person" GROUP BY "job" ORDER BY AVG("age") DESC