Following our introduction to working with files in Chapter 3, Transforming Files, this chapter worked through some common integration scenarios with one of the mainstays of modern applications, the relational database. We set up a database connection as project metadata that could be reused on many jobs. We learnt how to extract simple data from a database (from a single table), and two different ways that we might extract and join data from multiple tables. We created jobs that wrote data to a database, first from a flat file to a database and secondly, from database to database. We learned how to modify data in a database table and, finally, we learned about the dynamic database lookup based on information from an input data source.
Our next chapter will reuse some of the techniques we discovered in Chapters 3, Transforming Files and in this chapter, to help us understand how to implement some common data operation functions, sorting, filtering, aggregating, and normalizing.
