Dax Measure to return a single value from a column when using Min function on a different column

[JamesCarter]

Hi
I need to create a measure (and it has to be a measure, not a column, due wider reports/ calculations/ interdependencies). I need that measure to return the Ref which relates to the first start date. In the event that the first start date occurs twice or more, I need it to return the first occurrence. 

Example data is below:

Ref	Start Date
123456	01/01/2021
789123	03/04/2021
456019	09/05/2021
839213	12/05/2021
127459	01/01/2021
293022	27/02/2021
934859	13/02/2021
294850	15/04/2021
930573	18/04/2021
2938502	29/05/2021
754392	23/03/2021

So, from my data above, the first start date is 01/01/21 - that occurs with refs 123456 and 127459, so I'd want the answer to be 123456. 

I can obviously get a measure which lists the first start date using Min, but beyond that I'm hitting a wall.

Would be very grateful for any advice.
Thanks

[parry2k · Accepted solution]

@JamesCarter try this meaure

Top Ref = CALCULATE ( MIN ( Ref[Ref] ), TOPN ( 1, ALLSELECTED ( Ref ), Ref[Start Date], ASC ) )

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[Ashish_Mathur · Accepted solution]

Hi,

Try these measures

First date = MIN(Data[Start Date])

Measure = FIRSTNONBLANK ( TOPN ( 1, VALUES (Data[Ref]), [First date],ASC ), 1 )

Drag the second measure to a card visual.  The result will be 123456.

[JamesCarter]

Actually ignore that bit about variable. 
I thought it had worked, but it hadn't - so I've reverted to what you did and that remains perfect.

Thanks again
James

[JamesCarter]

Thanks Ashish, 
Absolute superstar. That worked a treat. 
I tweaked slightly to make the first measure a variable and I'm absolutely getting the result. 
Brilliant stuff - very grateful. I'd been playing with FIRSTNONBLANK, MIN and TOPN but just couldn't get it - haven't used ASC before. That's a new string to the bow!
Thanks again

[Ashish_Mathur]

You are welcome.

[parry2k · Accepted solution]

@JamesCarter try this meaure

Top Ref = CALCULATE ( MIN ( Ref[Ref] ), TOPN ( 1, ALLSELECTED ( Ref ), Ref[Start Date], ASC ) )

Check my latest blog post Comparing Selected Client With Other Top N Clients | PeryTUS  I would ❤ Kudos if my solution helped. 👉 If you can spend time posting the question, you can also make efforts to give Kudos to whoever helped to solve your problem. It is a token of appreciation!

⚡Visit us at https://perytus.com, your one-stop-shop for Power BI-related projects/training/consultancy.⚡

[JamesCarter]

Hi @parry2k 
I really should properly wait to investigate before replying - lesson for the future.
I've found what I did wrong in the previous attempt and yes, absolutely, your solution worked.
Thanks again

[JamesCarter]

Hi @parry2k 
Thanks so much for responding and for your proposal. 
I couldn't quite get it to work (it wouldn't let me call the start date). Sure it's something I did wrong in translating the measure to my actual table. 
Happily @Ashish_Mathur 's solution worked, but I'm really grateful for your time and offer of help.
I do love the support people offer on these forums.
Thanks again
James