Hello, I've been set a 'challenge' query. Basically if a certain column has NULL values, I need to replace those NULL values with another value (obtained from a subquery). So I thought, hey that's easy, I'll use ISNULL/COALESCE however I've been told I can't and instead I can only use JOINS/UNIONS and IS NULL. Unfortunately I don't know where to start. I was wondering if you could give me some pointers as to how it would be done generally using JOINS/UNIONS and IS NULL. Thanks in advance.