SELECT count(*) FROM student AS T1 JOIN has_pet AS T2 ON T1.stuid  =  T2.stuid WHERE T1.age  >  20
How many pets are owned by students that have an age greater than 20?
SELECT count ( * ) FROM student AS T1 JOIN has_pet AS T2 ON T1.stuid = T2.stuid WHERE T1.age > 20
select count ( * ) from student as t1 join has_pet as t2 on t1 . stuid = t2 . stuid where t1 . age > value
How many pets are owned by students that have an age greater than 20 ?