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 student ( stuid number, lname text, fname text, age number, sex text, major number, advisor number, city_code text )
TABLE: CREATE TABLE has_amenity ( dormid number, amenid number )
TABLE: CREATE TABLE dorm ( dormid number, dorm_name text, student_capacity number, gender text )
TABLE: CREATE TABLE lives_in ( stuid number, dormid number, room_number number )
TABLE: CREATE TABLE dorm_amenity ( amenid number, amenity_name text )

### Question ###
Find the number of students who is older than 20 in each dorm.

### Accurate SQL ###

SELECT COUNT(*), T3.dorm_name FROM student AS T1 JOIN lives_in AS T2 ON T1.stuid = T2.stuid JOIN dorm AS T3 ON T3.dormid = T2.dormid WHERE T1.age > 20 GROUP BY T3.dorm_name