Pull primary key from one table as foreign key in another

[EthelAppSheet]

Hi, 

I am trying to get a key from one table to populate a column in another table. Here is the relationship: 

1. Someone fills out the google form, which pulls data into a spreadsheet (SIF). An appscript inserts a key into column [SIF key]. 

2. A slice from SIF is presented as a ref list in another table (Students). When you click on the specific person, you can create a profile of that person in Student. This new record has the key: [Appsheet Key]. 

3. There is a column in SIF labeled [Student Key] where I would like the [Appsheet Key] to be autofilled once that person has been chosen from the ref list to become a profile in Student. 

I tried putting in "SELECT(STUDENT[Key],([_ComputedName] = [Full Name]))" into initial value in SIF{Student Key] but it didn't fill in when a new record in Student was made. 

Thanks for your help!

[Marc_Dillon]

App Formulas in real columns only evaluate when that record is edited. Virtual Columns re-evaluate upon every sync.

[EthelAppSheet]

I want the column to exist in my spreadsheet, so I actually don't want a virtual column. How can I do this with a regular column? Do I need to use actions and a bot, or is there a formula I can use?

[Marc_Dillon]

I did not intend to recommend using a VC. It's just an explanation that I have saved in my clipboard manager because it's a common misunderstanding. Your existing expression looks fine, though maybe wrap it in ANY(). You just need to make an edit to that record for it to re-evaluate. There are many ways to do so; manually, form save action, bot, etc.