This chapter looked at some of the advanced features of SQL, including the various types of joins: inner, left outer, right outer, and full outer. Star joins, which are used in support of star schemas, were also examined.
SQL can become very useful for solving complex business problems by using such features as CASE expressions, nested table expressions, UNIONs, and subqueries. These features allow us to push a lot of business logic into the SQL statement.
This chapter also looked at the classification of predicates and how to most efficiently code them to minimize the amount of data returned.