Lecture Notes: Summarize Columns in DAX

Introduction

• Speaker: Jeremiah Hersey
• Series: 6-part series on Virtual Tables
• Topic: Summarize Columns Function

Summarize Columns Function Overview

• Acts as an all-in-one function:
  • Group by (like SUMMARIZE)
  • Add columns (like ADDCOLUMNS)
  • Filter (like CALCULATE TABLE)
• Designed for running queries
• Not recommended for use inside measures due to filter context issues causing context transition problems
• Note: Extensive capabilities not fully covered in this video

Practical Example in Power BI Desktop

• Create New Table: Demonstration on creating a table using Summarize Columns
• Grouping:
  • Example groups by Product Class and Year
  • Use of columns from Date table
• Adding Columns:
  • Example adds a column for Total Sales
  • Default behavior removes rows with blank values

Handling Blanks

• Ignore Function:
  • Used to retain blank values in result set
  • Example shows blank values returning in the Amount column when using IGNORE function

Advanced Features (Not Demonstrated)

• Roll-up or Subtotal Columns:
  • Using ROLLUP, ADDSUBTOTAL, and ROLLUPGROUP

Filtering with Summarize Columns

• Adding Filters to Queries:
  • Example adds filter on Marital Status to show only Single
  • Change in filters dynamically updates table data
  • Demonstrates filter change from Single to Married and resulting data change

Important Considerations

• Context Transition Issue:
  • Summarize Columns does not function properly if external filter context causes context transition
  • For measures, better to use combination of ADDCOLUMNS and SUMMARIZE
• Usage Recommendation:
  • Suitable for queries but be cautious in measures

Conclusion and Upcoming Series

• Completion of the 6-part series on Virtual Tables
• Announced upcoming series on Introduction to Power BI
  • Basics, navigation, and tools in Power BI Desktop and Power Query Editor
• Call to action:
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