CREATE TABLE CUSTOMER (CustomerId VARCHAR, FirstName VARCHAR); CREATE TABLE INVOICE (InvoiceDate VARCHAR, CustomerId VARCHAR)
Find all invoice dates corresponding to customers with first name Astrid and last name Gruber.
SELECT T2.InvoiceDate FROM CUSTOMER AS T1 JOIN INVOICE AS T2 ON T1.CustomerId = T2.CustomerId WHERE T1.FirstName = "Astrid" AND LastName = "Gruber"