Database: warehouse_1 (difficulty: simple)
Question: Find the location of the warehouses which have contents Rocks but not Scissors.
SQL: SELECT T2.location FROM boxes AS T1 JOIN warehouses AS T2 ON T1.warehouse  =  T2.code WHERE T1.contents  =  'Rocks' EXCEPT SELECT T2.location FROM boxes AS T1 JOIN warehouses AS T2 ON T1.warehouse  =  T2.code WHERE T1.contents  =  'Scissors'