"select * from Students" "select * from Books where studentId=?"
Here you have 1 select statement for the student and if you have n number of students you have to fire n more query to select the books. So at the last you have to put n+1 select statement in order to perform this operation.
Now the next question is how to solve it ?
Using join fetching(it will join the parent and children and fetch all the information in a single statement) we can able to solve n+1 problem. Now our next query will look like this
"from Students s join fetch s.Books b"