If you can solve these patterns, you can solve 80%+ of SQL interview questions. 👇
🔹 Find the 2nd / Nth Highest Salary →
DENSE_RANK(), ROW_NUMBER()🔹 Find the Top 3 Customers in Each City →
PARTITION BY + Ranking Functions🔹 Detect Duplicate Records →
GROUP BY + HAVING COUNT(*) > 1🔹 Remove Duplicate Rows →
ROW_NUMBER() + CTE🔹 Calculate Running Total →
SUM() OVER()🔹 Compare Current vs Previous Row →
LAG()🔹 Compare Current vs Next Row →
LEAD()🔹 Find Employees Earning Above Department Average → Subquery / CTE
🔹 Find Customers Who Never Ordered →
LEFT JOIN / NOT EXISTS🔹 Find the Longest Consecutive Login Streak → Gaps & Islands
🔹 Calculate Month-over-Month Growth →
LAG() + Date Functions🔹 Find the First / Last Order of Every Customer →
ROW_NUMBER()🔹 Find Missing Dates or IDs → Calendar Table / Recursive CTE
❤️ React if you want more SQL interview patterns like these!
