Connecting to Sources and Transforming Data with M

This chapter follows the environment and data source preparation described in Chapter 2, Preparing Data Sources, by implementing Power Query (M) queries in a new Power BI Desktop file to retrieve the required fact and dimension tables. Power Query queries are written in a data transformation language commonly called “M” or can be generated via the Power Query Editor user interface. These queries access data sources and optionally apply data transformation logic to prep the tables for the Power BI data model.

Power Query (M) expressions are becoming ubiquitous throughout the entire Microsoft data platform. These expressions are used with dataflows, which are reusable by multiple Power BI datasets. They are also supported by Azure Data Factory (ADF) meaning that data mashup processes that begin in Power BI can be scaled up if necessary. Finally, M queries underpin dataflows within Dataverse, Microsoft’s operational...