Summary
We began this chapter by discussing the concept of a set. Next, we discussed each of the major set operations implemented in SQL in detail—intersection, difference, and union. We showed how to use set diagrams to visualize the problem you’re trying to solve. Finally, we introduced you to the basic SQL syntax and keywords (INTERSECT, EXCEPT, and UNION) for all three operations just to whet your appetite.
At this point you’re probably saying, “Wait a minute, why did you show me three kinds of set operations—two of which I probably can’t use?” Remember the title of the chapter: Thinking in Sets. If you’re going to be at all successful solving complex problems, you’ll need to break your problem into result sets of information that you then ...
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