CREATE TABLE church (church_id NUMBER, name CLOB, organized_by CLOB, open_date NUMBER, continuation_of CLOB)
CREATE TABLE people (people_id NUMBER, name CLOB, country CLOB, is_male CLOB, age NUMBER)
CREATE TABLE wedding (church_id NUMBER, male_id NUMBER, female_id NUMBER, year NUMBER)

Show the country where people older than 30 and younger than 25 are from.
SELECT country FROM people WHERE age < 25 INTERSECT SELECT country FROM people WHERE age > 30
SELECT "country" FROM "people" WHERE "age" < 25 INTERSECT SELECT "country" FROM "people" WHERE "age" > 30