Here is my scenario:

Multiple people perform maintenance on Master Items. When they complete, they take a picture of the item and that image gets posted to an Item Image table. One Master Item may have 0 to Many Item Images.

To save time for personnel, when a new maintenance Item Image is captured, that latest image is copied back into a ‘Current Image’ field in the Master Item table (replacing any prior). 

I want to place the code in a trigger. How do I structure the code to copy the image back to the right parent record?

let a := last(select ‘item image’) 

help>> where ‘master item id’ = ‘item image’.’master item id’

‘Master Item’.’Current Image’ := a.Image