-- Database schema
| Person : name [ TEXT ] primary_key , age [ INT ] , city [ TEXT ] , gender [ TEXT ] , job [ TEXT ] | PersonFriend : name [ TEXT ] PersonFriend.name = Person.name , friend [ TEXT ] PersonFriend.friend = Person.name , year [ INT ] |
-- -- How many people whose age is greater 30 and job is engineer?

SELECT count(*) FROM Person WHERE age  >  30 AND job  =  'engineer';