I have a list of names in a REF column. I would like to limit my users to entering only one REF record per name. Therefore, I would like to apply a valid_if statement to the REF column to remove options for which a record already exists.
I am wracking my brain trying to get this to workโฆ I have tried so many combinations of SELECT() and IN() that Iโm sure Iโm working in circles at this point.
Has anyone done this before that can give some insight?
LinkedIn
Twitter
