You have an employee table. You want the top 3 highest-paid employees in every department. Self-joins and counting (messy, slow). The Cookbook Way (Window Function):
Most developers know ORDER BY . But this chapter goes deep. How do you sort by a specific substring? How do you handle NULL values—should they come first or last? (Hint: It varies by database.) The 2nd Edition provides explicit recipes to control NULL sorting behavior across Oracle, SQL Server, and PostgreSQL. sql cookbook 2nd edition