Label to return next free list number?

[MarkB1977]

Evening all. 

Quick question.  I have a power app writing to a SP list. 

The list has unique reference numbers manually entered 2001, 2002, 2003 etc.

What I want is a label (I will place in the edit screen) to lookup the last used reference number and add 1.  Essentially providing the next reference number to enter. 

So if the last number in the list is 2009.

The label would return 2010

Thanks in advance. 

[eka24]

In the label try

First(Sort(Datasource,ID, Descending)).ID

This will give the last ID.

To Add

First(Sort(Datasource,ID, Descending)).ID+1

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[Roser · Accepted solution]

If you have more than 2000 items I would first sort the list in reverse order and pick the first item.

Value(First(Sort(YourList,Created,Descending)).ReferenceNumber)+1

While we are at it, why you don't just use the already existing ID field, which just does this for you automatically?

[MarkB1977]

@Roser 

That worked perfectly thank you.

I eventually went with 

If(IsBlank(DataCardValue10), Value(First(Sort('Drug and Alcohol Testing List',Created,Descending)).'Reference Number:')+1,"")

to only show the next number when the datacard was blank.

The ID field doesn't allow me to change the numbering system each year eg

2001 for Y2020

2101 for Y2021

2201 for Y2022

It also would leave a gap should an entry be deleted which doesn't look good in a list when presented as data IMO.