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joelv67
Frequent Visitor

List.First(List.Select()) comparing column table to containing table

background:

I have in my main table a CreateDate. I have created a column of data from the main table, for each row, it contains 1 or more records. I am trying to grab the First Date from the newtable where the CreateDate is < the current Records CreateDate.

 

Previosly, I was grabbing First record like so:

= Table.AddColumn(#"Merged Queries1", "StartDate", each List.First([NewTable][CreateDate]))

 

This grabs the CreateDate correctly, but just grabbign the 1st regardless.

 

I would like to change this to something like this:
= Table.AddColumn(#"Added Custom3", "StartDate2", each List.First( List.Select([NewTable][CreateDate], _ < [CreateDate] )))

 

I get the following error:
Expression.Error: We cannot apply operator > to types Record and DateTime.
Details:
    Operator=>
    Left=Record
    Right=1/12/2017 12:02:31 AM

 

Any ideas on how I can do this?

Sample Data:
CreateDate | Application | Severity | NewTable

1/12/2017 12:02:31 | TestApp | Info | <table>

 

<table> contents:
1/12/2017 12:01:00 | TestApp | Info

1/13/2017 12:01:00 | TestApp | Info

 

Thank you for any help

 

Joel

1 ACCEPTED SOLUTION

sorry, there was an Earlier missing:

 

= Table.AddColumn(#"Added Custom3", "StartDate2", (Earlier) => List.First( List.Select(Earlier[NewTable][CreateDate], each _ < Earlier[CreateDate] )))

 

Imke Feldmann (The BIccountant)

If you liked my solution, please give it a thumbs up. And if I did answer your question, please mark this post as a solution. Thanks!

How to integrate M-code into your solution -- How to get your questions answered quickly -- How to provide sample data -- Check out more PBI- learning resources here -- Performance Tipps for M-queries

View solution in original post

4 REPLIES 4
ImkeF
Super User
Super User

Pls try:

 

= Table.AddColumn(#"Added Custom3", "StartDate2", (Earlier) => List.First( List.Select([NewTable][CreateDate], each _ < Earlier[CreateDate] )))

Imke Feldmann (The BIccountant)

If you liked my solution, please give it a thumbs up. And if I did answer your question, please mark this post as a solution. Thanks!

How to integrate M-code into your solution -- How to get your questions answered quickly -- How to provide sample data -- Check out more PBI- learning resources here -- Performance Tipps for M-queries

joelv67
Frequent Visitor

Thank you for the quick response. I am now getting this error:

Expression.Error: There is an unknown identifier. Did you use the [field] shorthand for a _[field] outside of an 'each' expression?

sorry, there was an Earlier missing:

 

= Table.AddColumn(#"Added Custom3", "StartDate2", (Earlier) => List.First( List.Select(Earlier[NewTable][CreateDate], each _ < Earlier[CreateDate] )))

 

Imke Feldmann (The BIccountant)

If you liked my solution, please give it a thumbs up. And if I did answer your question, please mark this post as a solution. Thanks!

How to integrate M-code into your solution -- How to get your questions answered quickly -- How to provide sample data -- Check out more PBI- learning resources here -- Performance Tipps for M-queries

joelv67
Frequent Visitor

Thank you so much!

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