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>Very nice - I'd suggest you avoid arbitrarily assigning a, b, c. t1 and t2 would be a little more appropriate than a, b.

99% of the time I'd agree. I personally hate things like

select from order a , orderdetail b, ordernotes c, customer d



In this specific situation, with a single self-join, a and b are (to me, at least) no more/no less descriptive then t1 and t2. Both the 'b' and 't2' would indicate the 2nd instance. But in general I understand where you're coming from.

On the book....actually, I have decided to do a video course instead of a book. After 9 years of writing articles and being involved in 2 books, I am tired of formal writing. Would rather do webcasts and video content instead.