ETL Processing with SQL
Randal Root, Caryn Mason · Apress eBooks · 2012
The ETL process, and projects associated with it, involve extracting vital information from outside sources, transforming data into clean, consistent, and usable data, and loading it into the data warehouse. This process is vital to the success of your BI solution. It is what makes the difference between a professional, functional data warehouse versus one that is messy, insufficient, and unusable. The ETL process is also one of the longest and most challenging steps in developing a BI solution.