Actually, I am not looking to update the records already created or delete any of them, I am just looking for a way to control what gets added to the resultset based on the current contents of the resultset, but currently, it looks like even that is not possible with a recursive CTE. You can only control what gets added using global criteria that have to be decided upon a priori. Somewhat disappointing, but I learned something important about recursive CTE's that was not obvious in the documentation. Thank you to everyone on this forum who contributed to this learning.