How to Think Like the SQL Server Engine Part 3

We finished part 2 by adding a nonclustered index. Now, let's see all the ways that makes our query go faster. Then, we'll add more columns to our query so that the index isn't covering anymore, and we'll force SQL Server to make a tough decision: do lots of key lookups, or just scan the table? Then we'll learn how SQL Server uses statistics to make that decision.