Welcome to another practical and powerful SQL tutorial from DataFuture!
In this video, we tackle a real-time SQL interview question that many candidates face in top companies:
🔹 "How do you find users who were active for at least 4 continuous days?"
I will walk you step-by-step through solving this using:
✅ ROW_NUMBER() for tracking activity order
✅ A clever use of date arithmetic (DATE_SUB)
✅ Grouping logic to find consecutive activity streaks
✅ Filtering out only those users who qualify
This is an intermediate to advanced SQL use-case, but don't worry I will explain everything in a very simple way that freshers can easily follow and experienced developers will appreciate.
🧑💻 What You'll Learn:
How to detect continuous dates using SQL
Smart tricks with ROW_NUMBER() and date subtraction
Step-by-step debugging using intermediate CTEs
How to write clean, logical SQL for data analysis interviews.
📚 Prerequisite: Window Functions
👉 If you’re new to ROW_NUMBER(), RANK(), or DENSE_RANK(), please watch this video first:
📺 https://youtu.be/L-livwIY0Sg?si=SlVmDOg95GDc3fyD
00:00 Introduction to SQL Series
01:15 Demo: Understanding Window Functions
03:15 Demo: Detecting Consecutive Dates
06:05 Grouping and Filtering Logic & Final SQL Query
06:55 Summary & Tips
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