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50 Must-Know SQL Concepts for Interviews👇 Core Concepts 1. SELECT, FROM, WHERE 2. ORDER BY, LIMIT 3. AND, OR, NOT, IN, BETWEEN 4. NULL & IS NULL 5. DISTINCT Aggregations 6. COUNT(), SUM(), AVG() 7. MIN(), MAX() 8. GROUP BY 9. HAVING Joins 10. INNER JOIN 11. LEFT JOIN 12. RIGHT JOIN 13. FULL OUTER JOIN 14. SELF JOIN 15. CROSS JOIN Subqueries & CTEs 16. Subquery in SELECT 17. Subquery in WHERE 18. WITH (Common Table Expression) 19. Correlated Subqueries Window Functions 20. ROW_NUMBER() 21. RANK(), DENSE_RANK() 22. LEAD(), LAG() 23. OVER(), PARTITION BY String & Date Functions 24. CONCAT(), LENGTH(), UPPER()/LOWER() 25. SUBSTRING(), REPLACE() 26. DATE(), NOW(), DATEDIFF() Advanced Features 27. CASE WHEN 28. IF() & IFNULL() 29. COALESCE() 30. Nested Queries 31. Temporary Tables 32. Views 33. Stored Procedures (Basic) 34. Indexes & Performance 35. Transactions (BEGIN, COMMIT, ROLLBACK) 36. Primary & Foreign Keys Analytics Use Cases 37. Cohort Analysis 38. Retention Metrics 39. Funnel Analysis 40. Rolling Averages 41. AB Testing Query Logic Best Practices 42. Aliasing (AS) 43. Use EXPLAIN to check query plan 44. Avoid SELECT \* in production 45. Proper indexing 46. Normalize vs Denormalize Real-Life Scenarios 47. Querying large datasets 48. Optimizing slow queries 49. Joining multiple large tables 50. Writing reusable queries