Subqueries as Filters
In Chapter 6, you learned how to filter the information retrieved by adding a WHERE clause. You also learned how to use both simple and complex comparisons to get only the rows you want in your result set. Now we’ll build on your skills and show you how to use a subquery as one of the comparison arguments to do more sophisticated filtering.
Figure 11-5. Filtering a result using a simple comparison predicate
As you remember from Figure 11-2, a value expression can be a subquery. In the simple example ...