Beyond Basics: Mastering SQL's LEAD, LAG, RANK, DENSE_RANK, and NTILE

Short summary

Master five advanced SQL window functions (LEAD, LAG, RANK, DENSE_RANK, NTILE) for time-series comparisons, competitive rankings, and percentile analysis. Each function solves specific analytics problems without self-joins or correlated subqueries. Includes realistic e-commerce, salary, and customer churn examples.

• •LEAD/LAG retrieve next/previous row values for comparing values across time periods
• •RANK/DENSE_RANK assign competition-style rankings; RANK skips after ties, DENSE_RANK never skips
• •NTILE divides ordered rows into equal percentile buckets for customer segmentation and quartile analysis

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