Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE Apartment_Facilities ( apt_id VARCHAR, facility_code VARCHAR )
TABLE: CREATE TABLE Apartments ( room_count INTEGER, apt_id VARCHAR )

### Question ###
Show the total number of rooms of all apartments with facility code 'Gym'.

### Accurate SQL ###

SELECT SUM(T2.room_count) FROM Apartment_Facilities AS T1 JOIN Apartments AS T2 ON T1.apt_id = T2.apt_id WHERE T1.facility_code = "Gym"