March 23, 2005 Dear Colleagues
SQL has changed a lot since I first used it in 1984, and I can’t think of a single change that hasn’t been for the better. One of the best improvements, to my way of thinking, is the addition of the JOIN clause in SELECT queries.
I have never liked the EXISTS predicate. I find it hard to read. Sometimes it is difficult to make EXISTS yield the results I want. Fortunately, I have found that the LEFT EXCEPTION JOIN makes a good substitute for EXISTS in many cases. The left exception join returns rows from the primary table that