CREATE TABLE employment (company_id NUMBER, people_id NUMBER, year_working NUMBER)
CREATE TABLE company (company_id NUMBER, name CLOB, headquarters CLOB, industry CLOB, sales_in_billion NUMBER, profits_in_billion NUMBER, assets_in_billion NUMBER, market_value_in_billion NUMBER)
CREATE TABLE people (people_id NUMBER, age NUMBER, name CLOB, nationality CLOB, graduation_college CLOB)

Show the most common headquarter for companies.
SELECT headquarters FROM company GROUP BY headquarters ORDER BY COUNT(*) DESC LIMIT 1
SELECT "headquarters" FROM "company" GROUP BY "headquarters" ORDER BY COUNT(*) DESC FETCH FIRST 1 ROWS ONLY