In this chapter, you learned how to work on groups of rows in very different ways. First of all, you learned to sort, a very simple but useful task. Then you learned to aggregate data obtaining statistics such as sum, count, average, and so on, and also calculating other useful numbers as for example the first or last value in a dataset. After that, you learned to transform your dataset by applying two very useful steps: Row Normaliser and Row denormaliser. They do a great task in quite a simple way. Finally, you used the Analytic Query step to grab and use values in rows different than the current one.
So far, you have been transforming data stored mainly in files. In the next chapter, we will start learning to work with databases, which will enrich a lot of your possibilities in the creation of Extract, Transform, and Load (ETL) processes.
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