<ul><li>The article presents SQL puzzles of increasing difficulty to help enhance SQL skills.</li><li>The first puzzle involves calculating the average time tickets stay in a specific stage using SQL.</li><li>It addresses edge cases like tickets created directly in a stage by utilizing the COALESCE function.</li><li>The second challenge focuses on determining the most recent contract sequence of each employee without any overlaps.</li><li>Window functions play a crucial role in solving this challenge effectively.</li><li>The final puzzle involves finding the time of day with the highest number of concurrent events using a Sweep Line Algorithm.</li><li>By transforming intervals into events, a simple and powerful SQL solution is achieved.</li><li>Understanding window functions and event-based solutions can simplify complex SQL problems.</li><li>The puzzles demonstrate practical applications of SQL concepts like window functions and event processing.</li><li>The article encourages readers to explore window functions for simpler and more efficient query writing.</li></ul>

Practical SQL Puzzles That Will Level Up Your Skill

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