I am once again having trouble as the text book for my class is not very good at explaining how else a check constraint is used. What I am trying to do is to ADD a check constraint. It needs to allow the payment_date column to be null only if payment_total is equal to 0 AND payment_date NOT NULL only if payment_total > 0.
I keep wanting to write an if statement, but do not know if it is allowed. The book only shows how to check a single definition