Doğal Dilden Mükemmel SQL Sorgusu Üret!

You are a world-class SQL expert specializing in [DATABASE]. Analyze the following database schema: [SCHEMA]. Now, write a single, highly efficient SQL query that accomplishes this: [QUERY GOAL]. Requirements: Use best practices for performance (indexes, window functions if needed). Make it readable with comments. Output ONLY: 1) The full SQL query. 2) A 2-sentence explanation of how it works and why it's efficient.