Re: DAX Unpivot

Skilled Sharer
49638 Views
Greg_Deckler
Super User
Super User

DAX Unpivot

At a recent user group meeting in Columbus Ohio, one of my members presented me with a problem they were having. The member was working with a SharePoint list and attempting to unpivot a number of columns on thousands of list items. For some reason, the unpivoting, specifically, was causing massive performance issues. Therefore, I suggested unpivoting the data in DAX instead and created this example for the member to demonstrate the technique. Fortunately, this worked very well and was very performant even at scale. So, if you are having trouble with unpivoting data in Power Query, this technique may work for you.

 

The original example data looks like this:

Name Date Column1 Column2 Column3 Column4 Column5 Column6
Meeting 1 Monday, January 1, 2018 Greg Jason        
Meeting 2 Friday, January 5, 2018 Jason Frank George Battina    
Meeting 3 Wednesday, January 10, 2018 John Greg Jason Battina George Frank

 

The DAX Unpivot formula is:

 

Table = 
FILTER(
    UNION(
        SELECTCOLUMNS('Table1',"Name",[Name],"Date",[Date],"Column1",[Column1]),
        SELECTCOLUMNS('Table1',"Name",[Name],"Date",[Date],"Column1",[Column2]),
        SELECTCOLUMNS('Table1',"Name",[Name],"Date",[Date],"Column1",[Column3]),
        SELECTCOLUMNS('Table1',"Name",[Name],"Date",[Date],"Column1",[Column4]),
        SELECTCOLUMNS('Table1',"Name",[Name],"Date",[Date],"Column1",[Column5]),
        SELECTCOLUMNS('Table1',"Name",[Name],"Date",[Date],"Column1",[Column6])
    ),
    [Column1]<>"")

 

This will make the above data look like this:

Name Date Column1
Meeting 1 1/1/2018 0:00 Greg
Meeting 2 1/5/2018 0:00 Jason
Meeting 3 1/10/2018 0:00 John
Meeting 1 1/1/2018 0:00 Jason
Meeting 2 1/5/2018 0:00 Frank
Meeting 3 1/10/2018 0:00 Greg
Meeting 2 1/5/2018 0:00 George
Meeting 3 1/10/2018 0:00 Jason
Meeting 2 1/5/2018 0:00 Battina
Meeting 3 1/10/2018 0:00 Battina
Meeting 3 1/10/2018 0:00 George
Meeting 3 1/10/2018 0:00 Frank

 

 

 



Follow on LinkedIn
@ me in replies or I'll lose your thread!!!
Instead of a Kudo, please vote for this idea
Become an expert!: Enterprise DNA
External Tools: MSHGQM
YouTube Channel!: Microsoft Hates Greg
Latest book!:
Power BI Cookbook Third Edition (Color)

DAX is easy, CALCULATE makes DAX hard...
pabeader
Post Patron
Post Patron

I think you need to add an 'addcolumn' in there to bring in the Column Heading information.  The way you have it now, assumes that the value data is all the same thing.  ie people.  But usually the different columns contain different 'types' of information like, color, size, cost, etc.  So that info needs to be included in the unpivot...

Nart
Frequent Visitor

This is great, but one thing is missing for me.
In the table on the right, the column headres are stored in the "Purchase type" column (what would be the Attribute column in Power Query), while this DAX code doesn't create that attribute column. Any ideas on how to achieve that?

BG123
Frequent Visitor

I am not sure what I amissing but I am with Nart, the column headers NEED to be dynamic. The Union trick is helpful but you are hardcoding "Column1", etc. How do we generate the "Purchase Type" column from large number of columns like attribute column in Power Query, except of course with distinct values...?

PoojaDarbhe
Resolver I
Resolver I

Hi @Greg_Deckler , 

 

This is awsome technique, I am trying to implement it but getting following error, could you please guide me on this. All columns which I am trying to unpivot are of date type you can see it on the right side in fields.

 

PoojaDarbhe_0-1601459253464.png

 

Thanks in advance.

Regards,

Pooja Darbhe

@PoojaDarbhe - I can't see all of the formula so not sure exactly where you are getting the error in your DAX. If we are talking about the last line in your screen shot, you could try to replace "" with BLANK().



Follow on LinkedIn
@ me in replies or I'll lose your thread!!!
Instead of a Kudo, please vote for this idea
Become an expert!: Enterprise DNA
External Tools: MSHGQM
YouTube Channel!: Microsoft Hates Greg
Latest book!:
Power BI Cookbook Third Edition (Color)

DAX is easy, CALCULATE makes DAX hard...
avatar user
Anonymous
Not applicable

Hi Greg_Deckler,

 

I have same error message as@PoojaDarbhe , i tred to change "" to (), then i got another error as below, please help, thanks. 

Jess_Lee_1-1623384680925.png

changed "" to () as suggested but got another error as below

 

Jess_Lee_0-1623384627490.png

 

Hi @Anonymous 

 

Write Blank(), that will solve your problem.

Let me know in case of any issues.

 

Best regards,

Pooja Darbhe

avatar user
Anonymous
Not applicable

Hi @PoojaDarbhe,

Did that but got the below error message, please help, thanks.

Jess_Lee_0-1623644846060.png

Hi @Anonymous ,

 

Instead of [Output All] write [Outputfg], it should be column name not the value.

 

Please try this and let me know if that works.

 

Best regards,

Pooja Darbhe

Hi @Greg_Deckler 

 

Thanks for the help, there was the problem with last line only.

 

Regards,

Pooja Darbhe

avatar user
Anonymous
Not applicable

That is a one brilliant solution, Thank You!

Thanks @Anonymous !


Follow on LinkedIn
@ me in replies or I'll lose your thread!!!
Instead of a Kudo, please vote for this idea
Become an expert!: Enterprise DNA
External Tools: MSHGQM
YouTube Channel!: Microsoft Hates Greg
Latest book!:
Power BI Cookbook Third Edition (Color)

DAX is easy, CALCULATE makes DAX hard...
anandav
Skilled Sharer
Skilled Sharer

interesting solution for unpivoting in DAX. 👍

DouweMeer
Post Prodigy
Post Prodigy

Hello @Greg_Deckler ,

 

Just stumbled upon your tip. I already knew it, but I was wondering, as the first section of selectcolumns is the same across all, can you bring in a string value created by DAX and apply it to the last bit? A little bit like using Indirect in Excel. 

avatar user