You’d probably be surprised that this is one of my most used functions within a dashboard. It is just such a cool
function. Though, it is almost exclusively used for UI/UX functionality.

Only()

“Only” is an aggregation function that can be used on a string field. If a single result comes back it will return the
result, if more than one values occur it returns null.

Example:

only

One of the best features is that you can use set analysis with it, which gives you a lot of control. It can be used
to pull out expression definitions stored in a field, used to create dynamic labels, and many other things.