Database: bakery_1
Question: What are the distinct ids of customers who bought lemon flavored cake?
SQL:
SELECT DISTINCT T3.CustomerId FROM goods AS T1 JOIN items AS T2 ON T1.Id  =  T2.Item JOIN receipts AS T3 ON T2.Receipt  =  T3.ReceiptNumber WHERE T1.Flavor  =  "Lemon" AND T1.Food  =  "Cake"