Power BI - Simplifying Calculated Columns and Measures

In Power BI, writing DAX (DATA ANALYSIS EXPRESSIONS) is all about creating Calculated Columns or Measures.

Let's try to break and simplify them:

Calculated Columns:

Introduction-

Calculated Columns are like any other columns in a table. They are like extension columns to your  initial table, which are created using DAX inside Power BI.

For example, we have a table called Employee with columns - Employee_ID & Employee_Name:

Employee_ID	Employee_Name
1	aDam
2	Bjorn
3	GoergE
4	Tim
5	RoN

The names of the employees are not entered in a proper format and the requirement is to CAPITALIZE them.

This can be achieved through multiple options, but as we are talking about Calculated Columns, let's create a new DAX column as follows:

Corrected_Name = UPPER(Employee[Employee_Name])

Employee_ID	Employee_Name	Corrected_Name
1	aDam	ADAM
2	Bjorn	BJORN
3	GoergE	GEORGE
4	Tim	TIM
5	RoN	RON

This calculation is computed at each ROW LEVEL. 

A Few Behaviors of Calculated Column(s)-

• Computed during Creation/Data Refresh
• Occupy space in the memory
  
• Represented by fx icon in the fields 
  

Measures:

Introduction-

If the requirement is to calculate an aggregate of many rows, then Measure is our best bet. These are dynamic in nature, meaning for each slicer/filter applied to the report, the measures are calculated on the go.

For example, we have a Region_Sales table as below:

Region_Name	Sales_Target	Sales_Achieved
North	1000	800
East	2000	1000
South	4000	1600
West	5000	500

The requirement is to calculate Achieved Sales %:

Achieved_Sales = Divide(Region_Sales[Sales_Achieved], Region_Sales[Sales_Target])

Region_Name	Sales_Target	Sales_Achieved	Achieved_Sales
North	1000	800	80%
East	2000	1000	50%
South	4000	1600	40%
West	5000	500	10%

A Few Behaviors of  Measure(s)-

• Although a measure is created using a table columns, they do not belong to any of the tables in the dataset. 
• Use CPU during the query time - Slicing/Cross filtering Visuals.
• Represented by a Calculator icon in the fields section