Context Considerations - (1.13) Ultimate Beginners Guide to DAX 2020

Follow along to the beginners guide DAX tutorials by using the demo data available for download. Enjoy!

Details of what you will learn during this course
Learn - what DAX is and why you need to learn it when using Power BI
Learn - the basics of DAX calculations
Understand - formula syntax, writing comments & variables
Review - how the data model and DAX calculations work together
Learn - what the most important concept of DAX is - CONTEXT
Understand - what the CALCULATE statement does
Learn - what table functions are and when to use them
Review - time intelligence functions
Understand - how important learning DAX well is when using Power BI

Here are the specifics for the course
Learn how to;
Use DAX formula with Power BI
When and where to use DAX functions
Utilise some of the great features built into the DAX formula bar
Use the data model in combination with DAX formula
Understand the concept of CONTEXT
Use the CALCULATE statement
Create filters using table functions
Incorporate time intelligence functions in your analysis
Become a DAX master by combining patterns of DAX formula

***** Learning Power BI? *****

[sreekumarmenonk]

Like always, 8 mins of pure Gold!
i have a question though, related to the DAX you have written (maybe out side the context of this videos).

My question is related to the Filter Expression of the Filter function, i.e.:
Dates[Date] > Max( Dates[Date]) - 30 &&
Dates[Date] <= Max( Dates[Date]

Here, does the LHS point to the Table (i.e. All(Dates)) and the RHS point to the evaluation context?
Is the Max function used in the RHS just for the sake of wrapping the 'Current Date Value' within a measure so that it can be used within the Filter function?

[ParthSahakne]

Hi Sam, really amazing style of teaching .... Great fan of yours...
Keep up the great work you are doing...

Thanks
Parth

[nickelvidge]

Hi Sam,
Great course and thank you very much for this and I am subscribed.
I have a question on this particular video. When you set the Filter within Calculate to use ALL(Dates) then I would then have thought that MAX(Dates[Date]) would return the very last date in the unfiltered Dates table. So, why is it then that MAX(Date[Dates[) actually returns the date of the row being evaluated? It seems that there is some extra context going on here i.e. the date of the row which is being evaluated. But then, how can CALCULATE be able to see all past dates (i.e. the -30 days) but nothing forward of the current row's date.

Would very much appreciate your opinion on this.

Thanks again Nick

[gulhermepereira]

Great video!
I´m not really sure about the running total though.. Should the line chart begin with 0 and end up with some value?

[artieboy]

What if you change the date column to products? You would have a 30 day running total of sales per product, but each window would (in theory) have a different 30 day range depending on the max sales date of the particular product. So my question is this: how do you freeze the date range at a specific 30 day window such that all products are evaluated over the same range of dates? If a product had no sales within that range it would return 0.

Any help would be appreciated. Cheers!

[usamatalha]

Great! Very much helpful. Thanks a lot <3

[hussammohamed]

would you please explain it more am not got it

[marliearcellia]

Hi Sam, can you pls help me. I’ve watched this video several times but still lost. How exactly the last two rows of the 30 Day Running Total Measure work? Thank you

[Golden_Tortoise]

I tried to use min() and max() function here and they both return the same result. It seems tht min() max() is just used and needed to reference the same row (its self) when dax is iterating through the table. So the logic makes sense but the syntex does not.

[Moon-Birdy]

Indeed, this formula is very difficult to be understood and the syntax is confusing - ie. which one is current value, which one is value of the iterator.
Max value in Dates table is 2021-12-31.
Assuming the current value of the iteration is at 2018-02-01, which has 31 values in Jan before it. (Total Sales = $62, 405, 30 days=3-Jan to 1-Feb)
FILTER( ALL(Dates),
Dates[Date] > MAX(Dates[Date]) - 30 &&
Dates[Date] <= MAX(Dates[Date]) )

1. ALL(Dates) --> Remove all filters, which means Max value is 2021-12-31

2a. replace the "variable" with value, current value is 2018-02-01
2018-02-01 > MAX(2018-02-01) - 30 &&
2018-02-01 <= MAX(2018-02-01)
it doesn't make sense, right? one of these "Dates[Date]" variable must be the current value of the iterator

2b. replace the "variable" with value, current value is 2018-02-01
, Max Date in Dates Table = 2021-12-31 as ALL filters are removed
Dates[Date] > 2021-12-31 - 30 &&
Dates[Date] <= 2021-12-31
it also doesn't seem right...

2c, replace the "variable" with value, current value is 2018-02-01
Dates[Date] > 2018-02-01 - 30 &&
Dates[Date] <= 2018-02-01
it seems to be right, but why MAX() return the current value, not the Max value of the table... and why we replace only the "variable"
inside the MAX(), not the outside one.

maybe my thinking is in the wrong track.... is there any rule on variable replacement?