topic Re: Date for Last two Friday's Dax in DAX Commands and Tips

Date for Last two Friday's Dax

Anonymous — Mon, 23 Aug 2021 16:37:05 GMT

Hi

For this week (today 23th august 2021) - I want to display two dates i.e last two fridays
1) Last Friday i.e 08/20/2021
2) Last Friday before 20th August,2021 i.e 08/13/2021

Can someone please help me with the DAX?

Thank you in advance.

Re: Date for Last two Friday's Dax

PaulDBrown — Mon, 23 Aug 2021 16:57:43 GMT

do you have a Calendar or Date table? Also, does the week begin on Sunday or Monday?

Re: Date for Last two Friday's Dax

Anonymous — Mon, 23 Aug 2021 17:06:10 GMT

I dont have a calendar nor date table. But I can definately create on based on your suggestion.

Re: Date for Last two Friday's Dax

PaulDBrown — Mon, 23 Aug 2021 17:09:34 GMT

you need one. Also, does the week start on Sunday or Monday?

Re: Date for Last two Friday's Dax

Anonymous — Mon, 23 Aug 2021 18:52:33 GMT

Anything would work. As far as I get to the friday's date

Re: Date for Last two Friday's Dax

PaulDBrown — Tue, 24 Aug 2021 07:51:48 GMT

OK. First create a Calendar Table.

Calendar Table = VAR MinD = DATE ( 2020, 12, 01 ) // subsitute for the expression for the minimum date in you model, as in MIN(Table1[Date]) VAR MaxD = DATE ( 2021, 10, 31 ) // subsitute for the expression for the maximum date in you model, as in MAX(Table2[Date]) - if the min and max dates are in the same table, use the same table expression. RETURN ADDCOLUMNS ( CALENDAR ( MinD, MaxD ), "WeekDay", WEEKDAY ( [Date], 2 ), "WeekNum", WEEKNUM ( [Date] ), "Year", YEAR ( [Date] ), "YearWeek", YEAR ( [Date] ) * 100 + WEEKNUM ( [Date] ) )

Add a new calculated column to this table to establish an index for the YearWeek field using:

Index = RANKX('Calendar Table', 'Calendar Table'[YearWeek],,ASC,Dense)

And you should get this final Calendar Table:

Now create the measure you need:

Last Friday = VAR YearWeek = CALCULATE ( MAX ( 'Calendar Table'[Index] ), FILTER ( 'Calendar Table' , 'Calendar Table'[Date] = TODAY () ) ) RETURN CALCULATE ( MAX ( 'Calendar Table'[Date] ), FILTER ( 'Calendar Table', 'Calendar Table'[Index] = YearWeek - 1 && 'Calendar Table'[WeekDay] = 5 ) )

And...

2 Friday Ago = VAR YearWeek = CALCULATE ( MAX ( 'Calendar Table'[Index] ), FILTER ( 'Calendar Table' , 'Calendar Table'[Date] = TODAY () ) ) RETURN CALCULATE ( MAX ( 'Calendar Table'[Date] ), FILTER ( 'Calendar Table', 'Calendar Table'[Index] = YearWeek - 2 && 'Calendar Table'[WeekDay] = 5 ) )

And you will get this:

Re: Date for Last two Friday's Dax

Anonymous — Mon, 23 Aug 2021 21:07:56 GMT

Thank you. This is super-helpful.

Re: Date for Last two Friday's Dax

PaulDBrown — Mon, 23 Aug 2021 21:29:36 GMT

Happy to have helped.
BTW, if you have date fields in your model you should be using the Calendar table as a dimension table by creating relationships with the corresponding date fields in your model. You can the use Time Intelligence functions in measures, and the fields from the Calendar table in your visuals, filters, slicers, measures etc