CREATE TABLE personfriend (name TEXT, friend TEXT, year DECIMAL)
CREATE TABLE person (name TEXT, age DECIMAL, city TEXT, gender TEXT, job TEXT)

How many people whose age is greater 30 and job is engineer?
SELECT COUNT(*) FROM person WHERE age > 30 AND job = 'engineer'
SELECT COUNT(*) FROM "person" WHERE "age" > 30 AND "job" = 'engineer'