Understanding Date functions

[yush_amateur]

Hi
Can someone please explain the difference between using 

DATEADD('Calendar'[Date].[Date], -1, Year)
and

DATEADD('Calendar'[Date], -1, Year)

Since I'm calculating Year On Year Sales, I'm getting different results from the two. 
Using dot Date is giving me 21.65%, but using only Date is giving me 110%.
Can Someone please explain how these two work, and which one is ideal to use?

Thank You.

[Anonymous · Accepted solution]

Hi @yush_amateur ,

The key difference between these two expressions lies in the use of the '[Date].[Date]' hierarchy versus the '[Date]' column.

When you use 'Calendar'[Date].[Date], you are referring to a specific level within a date hierarchy. In Power BI, hierarchies allow you to drill down through levels of data granularity. If you have a hierarchy that includes Year, Quarter, Month, and Day, using the [Date].[Date] part specifies that you want to perform the operation at the Day level of the hierarchy.

On the other hand, when you use 'Calendar'[Date], you are referring to the Date column itself without specifying a hierarchy level. This means the operation will be performed on the entire column, considering the granularity of the data in that column.

Best Regards,
Dino Tao
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