Attempting to query based on a data extension called [Users], but I want to extract ALL the contacts that are also in the [Unsubscribe] data extension.
I thought it would be a simple 'NOT IN' function, but do I need to INNER JOIN, as well?
SELECT * FROM ENT.[Users] WHERE Email Address NOT IN ENT.[Unsubscribe]
First if that's the "Email Address" field, you would have to put it in brackets [Email Address]. I suspect there is no space between them (EmailAddress).
I would use this as I have found it to work well for me when excluding fields present in another DE.