Power BI - Columns and Measures

Overview

Creating a new column or new measure both fundamentally do the same thing. They are both methods of manipulating data for easier visualization. For most purposes, creating a new column is the easier method, especially for users who are familier with Excel. The reason that a measure may be used, is that the new values created from it are calculated as they are needed, they are not stored. This means that when the column is hundreds of thousands, or even millions of values, a measure will keep the program running smoothly and quickly, whereas a new column may impact performance and size of the file.

DAX

DAX is a collection of functions, of which data can be manipulated and is the basis behind both columns and measures. If there is a large number of rows imported into Power BI, it is important to write your DAX expressions correctly to avoid the program slowing down. It has been shown that Power BI can support datasets with >a trillion rows with correctly written DAX. Some common DAX functions include (but are not even close to limited to):

• SUM: This adds all the numbers in the specified column (SUM(<column>))
• FILTER: The filter functions allows the manipulation of data context to create new calculations. This is one of the most useful DAX functions and creating a working knowledge of it is very powerful (FILTER(<table>,<filter>))
• COUNT: The count function counts the number of rows in a given column (COUNT(<column>))

Example

Here we will continue the example started on the Power BI page.

First, navigate to the dataview with the table icon on the left side of the window.