I am trying to create an automation process to filter out my least active subscribers and then unsubscribe them from my communications (my subscribers are saved as a salesforce data extension). I was able to perform the filter activity and send it to a new data extension. I am currently trying to create a SQL Query to change the contact id on this new data extension to 0 and then perform an INNER JOIN with the original data extension to essentially delete these subscribers from my data. The SQL query seems to be the problem:
SELECT [Contact ID] FROM ATest SET [Contact ID] = '0'
This was my first query but it gives me an error for invalid syntax near 'SET' (ATest being my data extension name). My 2nd query was gonna be the JOIN clause.
This is my 2nd week using Marketing Cloud and I just learned SQL so I welcome any better ideas on how to solve this or other ways to do this more easily.