CREATE TABLE lives_in (stuid VARCHAR2, dormid VARCHAR2)
CREATE TABLE student (age NUMBER, stuid VARCHAR2)
CREATE TABLE dorm (dorm_name VARCHAR2, dormid VARCHAR2)

Find the average age of students living in each dorm and the name of dorm.
SELECT AVG(T1.age), 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 GROUP BY T3.dorm_name
SELECT AVG("T1"."age"), "T3"."dorm_name" FROM "student" "T1" JOIN "lives_in" "T2" ON "T1"."stuid" = "T2"."stuid" JOIN "dorm" "T3" ON "T2"."dormid" = "T3"."dormid" GROUP BY "T3"."dorm_name"