Database: book_1
Question: What are the isbns of books ordered by both clients named Peter Doe and James Smith?
SQL:
SELECT T2.isbn FROM Orders AS T1 JOIN Books_Order AS T2 ON T1.idOrder  =  T2.idOrder JOIN Client AS T3 ON T1.idClient  =  T3.idClient WHERE T3.name  =  "Peter Doe" INTERSECT SELECT T2.isbn FROM Orders AS T1 JOIN Books_Order AS T2 ON T1.idOrder  =  T2.idOrder JOIN Client AS T3 ON T1.idClient  =  T3.idClient WHERE T3.name  =  "James Smith"