Dereference Expression Assistance

[mykrobinson]

I'm trying to work through a problem and am taking baby steps. Here's my original post:

https://www.googlecloudcommunity.com/gc/AppSheet-Q-A/Expression-Assistance-Text-Formatting-through-E...

But for today, I am just trying to dumb it down and create a virtual column to test expressions and figure out how to properly build what will fix my concern in the original question.

Today i am having trouble crafting a proper dereference. I have a virtual column in the PATIENTS table called CONCATENATE TEST. The current expression for that column is

SUBSTITUTE([Flags],"HFpEF",CONCATENATE("HFpEF"," - ",Echo[_patientIdentifier][LVEF]))

what i was hoping to have happen is this for this field to show the value of the [Flags] column in the PATIENTS record, but if HFpEF shows in the Flags value, to replace it with HFpEF -  then the value in the ECHO table's [LVEF] column, referenced by the _patientIdentifier.

If i place a dot between [_patientIdentifier] and [LVEF], i get an error that the column cannot be found. I think i have a made a few mistakes here and have gotten myself confused looking at tutorials 🙂

Little help?

Thanks

[mykrobinson]

bumping this so it doesn't get buried. WIll try a few other things this morning and see what i can figure out.

[Aurelien]

Hi @mykrobinson 

I suggest:

SUBSTITUTE(
  [Flags],
  "HFpEF",
  CONCATENATE("HFpEF"," - ",[_patientIdentifier].[Echo].[LVEF])
)

For reference:

Dereference expressions - AppSheet Help