use Pig and Spark SQL to solve the analytic problems for a set of linked tables. Now we have three data files with the following schema: customer(cid, name, age, city, sex), book(isbn, name), and purchase(year, cid, isbn, seller, price), where [login to view URL] is the foreign key to [login to view URL] and [login to view URL] is the foreign key to book.isbn. The fields in the dataset are separated by "\t". You should assign the schema, i.e., field names and and types, to the fields when you load the data.