Database: bakery_1
Question: What are the receipt numbers for instances where both cakes and cookies were purchased?
SQL:
SELECT T1.receipt FROM items AS T1 JOIN goods AS T2 ON T1.item  =  T2.id WHERE T2.food  =  "Cake" INTERSECT SELECT T1.receipt FROM items AS T1 JOIN goods AS T2 ON T1.item  =  T2.id WHERE T2.food  =  "Cookie"