Schema: CREATE TABLE Reservations (firstname VARCHAR, lastname VARCHAR, Room VARCHAR, Rate VARCHAR); CREATE TABLE Rooms (RoomId VARCHAR, basePrice VARCHAR)
Question: Find the first and last names of people who payed more than the rooms' base prices.
SQL: SELECT T1.firstname, T1.lastname FROM Reservations AS T1 JOIN Rooms AS T2 ON T1.Room = T2.RoomId WHERE T1.Rate - T2.basePrice > 0