Introduction

When you first create a semantic model by applying Power Query queries, the model consists of tables and columns. At this point, the model probably isn't ready for use. That's because you might need to create or adjust model relationships, create other tables or columns, add hierarchies, or set model properties. You might also identify the need for calculations to summarize the model data, especially when the requirement can't be achieved by summarizing a single column. For example, you might want to calculate year-to-date (YTD) sales revenue, which requires special time filters.

You can use Data Analysis Expressions (DAX) to add three types of calculations to your semantic model to complete your model design:

• Calculated tables, which can be useful to create date tables or role-playing dimensions, or to enable what-if analysis.
• Calculated columns, which can be added to tables in your model.
• Measures, which achieve summarization over model data.

In this module, you learn why and how to create each of these calculation types.