Advanced SQL Window Functions Explained | CTEs, Ranking, LAG, LEAD & Interview Challenges
Learn Advanced SQL step by step with clear visual examples and interview-style challenges.
In this video, we explain key SQL concepts every Data Engineer and Analyst should know, including CTEs, subqueries, window functions, ranking functions, date functions, string functions, and conditional aggregations.
You will learn how to solve common real-world SQL problems such as finding the latest order per customer, detecting duplicated records, calculating running totals, comparing current rows vs previous rows, finding month-over-month growth, and returning the top 3 products per category.
Topics covered:
00:00 Advanced SQL Roadmap
01:47 CTEs vs Subqueries
04:29 Window Functions fundamentals
06:26 ROW_NUMBER, RANK, and DENSE_RANK (Ranking Functions)
08:20 LAG and LEAD
09:58 SUM OVER, AVG OVER, and COUNT OVER (Running Totals and Moving Metrics)
11:43 Date functions for month-over-month growth
14:06 String functions and conditional aggregations
15:37 SQL interview challenge patterns
This video is perfect for Data Engineers, Data Analysts, SQL developers, and anyone preparing for technical interviews.