Assume the data warehousing system is centralized, and implemented in the environment of Microsoft SQL Server 2012. As we discussed in the introduction, each store has its own local database. Therefore, you can think the source data include both the operational databases
for ordering and stores' local databases. After a customer returned a car successfully, the system should create a record for this customer and save the record into the central data warehouse.

It is essential to the business to maintain qualified data in the data warehouse. Therefore, you are required to design an ETL process for this question. You are required to decide an application (ETL or ELT) first and then discuss the advantages and/or disadvantages of your proposed application . You also need to define ETL functions to clearly understand what data the data warehouse has and what data the data warehouse does not have.