SQL Challenge: Find Golden Hour Customers

Day 10/50 – #SQLChallenge 🚀 Solved “Managers with at Least 5 Direct Reports” problem on LeetCode. ✅ Approach: Used subquery with GROUP BY and HAVING ✅ Key Concept: Aggregating data to filter groups based on count 💡 Advanced Insight: The HAVING clause is applied after grouping, making it ideal for filtering aggregated results (like COUNT). This is different from WHERE, which filters rows before grouping. Understanding this distinction is key when working with real-world data. 🔍 Takeaway: Combining subqueries with aggregation helps solve hierarchical data problems like identifying managers and their reporting structure. 10 days of consistency — building strong fundamentals 💪 #SQL #LeetCode #Database #CodingChallenge #ProblemSolving #LearningInPublic #DeveloperJourney

❄️ LeetCode Daily Challenge 📅 Day 40 of 50 Days SQL Challenge Today’s challenge focused on subscription funnel analysis — a common real-world business analytics use case 📈 📌 Problem: Analyze Subscription Conversion 🔗Problem Link: https://lnkd.in/gSEZWxJb 💡 Problem Breakdown: Identify users who converted from free trial to paid subscription: ✔ Find users who moved from free_trial to paid ✔ Calculate average daily activity duration during free trial ✔ Calculate average daily activity duration during paid period ✔ Round averages to 2 decimal places 40 days of consistent SQL practice completed ✅ Daily practice is turning concepts into intuition 💪 Let’s grow one query at a time 🚀 💬 How would you approach this? Single query with conditional aggregation or separate CTEs? Drop your thoughts below 👇 #LeetCode #SQL #DataEngineering #AzureDataEngineer #ProductAnalytics #SQLPractice #LearningInPublic #50DaysChallenge #DataAnalytics

❄️ LeetCode Daily Challenge 📅 Day 28 of 50 Days SQL Challenge Continuing my SQL consistency journey with a Medium-level SQL problem focused on user behavior analysis and aggregation. 📌 Problem: Find Emotionally Consistent Users 🔗 Problem Link: https://lnkd.in/gwAXyQGJ 💡 Problem Summary: Identify users who are emotionally consistent based on their reactions: ✔ At least 5 reactions ✔ At least 60% of reactions are the same type ✔ Return dominant reaction + ratio 28 days of consistent SQL practice completed ✅ Consistency is turning into clarity 💪 Let’s grow one query at a time 🚀 #LeetCode #SQL #DataEngineering #Analytics #UserBehavior #DataAnalysis #WindowFunctions #DailyPractice #LearningInPublic #50DaysChallenge

🚀 Day 30/100 – LeetCode SQL Challenge ✅ Problem Solved: Reformat Department Table Today’s problem focused on transforming row-based data into a structured column format — a common real-world data handling task. 🔍 What I Learned: How to use CASE WHEN in SQL for conditional aggregation Converting rows into columns (pivoting data) Importance of GROUP BY for summarizing data Handling missing values using NULL 💡 My Approach: Grouped data by department id Used SUM(CASE WHEN month = 'Jan' THEN revenue END) pattern Repeated this logic for all 12 months Ensured each month becomes a separate column 📊 This problem helped me understand how SQL can reshape data effectively for reporting and dashboards. 🔥 Consistency is the key — 30 days done, 70 more to go! #Day30 #100DaysOfCode #LeetCode #SQL #DataAnalytics #CodingJourney #PlacementPreparation

❄️ LeetCode Daily Challenge 📅 Day 30 of 50 Days SQL Challenge Today’s challenge was a deep dive into subscription analytics and churn prediction — something very relevant to real-world data scenarios. 📌 Problem: Find Churn Risk Customers 🔗Problem Link: https://lnkd.in/dw95yEPj 💡 Problem Breakdown: Identify churn risk customers who: ✔ Currently have an active subscription (last event is not cancel) ✔ Have at least one downgrade in their history ✔ Current plan revenue < 50% of their historical maximum ✔ Have been subscribed for at least 60 days 30 days of consistent SQL practice completed ✅ Daily practice is turning concepts into intuition 💪 Let’s grow one query at a time 🚀 Drop your approach below 👇 #LeetCode #SQL #DataEngineering #Analytics #ChurnAnalysis #CustomerRetention #SQLPractice #WindowFunctions #LearningInPublic #50DaysChallenge

❄️ LeetCode Daily Challenge 📅 Day 21 of 50 Days SQL Challenge Continuing my SQL consistency journey with a Medium-level SQL problem focused on joins and conditional aggregation. 📌 Problem : Market Analysis I 🔗 Problem Link : https://lnkd.in/gK6uAEEJ 💡 Problem Summary : For each user, we need to find: ✔ Their join date ✔ Number of orders they made as a buyer in 2019 Important: Include users with 0 orders Count only orders from 2019 21 days of SQL practice done ✅ Consistency is building real confidence now 💪 Let’s grow one query at a time 🚀 #LeetCode #SQL #DataEngineering #Analytics #Database #WindowFunctions #DailyPractice #LearningInPublic #50DaysChallenge

Day 9/50 – #SQLChallenge 🚀 Solved “Rising Temperature” problem on LeetCode. ✅ Approach: Used SELF JOIN to compare rows within the same table ✅ Key Concept: Comparing consecutive records using date difference 💡 Advanced Insight: Since SQL doesn’t have a direct way to access the previous row, a SELF JOIN helps simulate this behavior by pairing each record with its previous day. This pattern is widely used in time-series data analysis. 🔍 Takeaway: Understanding how to compare rows across time is crucial for real-world scenarios like tracking growth, trends, and performance metrics. Consistency is compounding 📈 #SQL #LeetCode #Database #Joins #CodingChallenge #ProblemSolving #LearningInPublic #DeveloperJourney

❄️ LeetCode Daily Challenge 📅 Day 34 of 50 Days SQL Challenge Today’s challenge was all about analyzing performance improvement over time — a very practical scenario in real-world analytics. 📌 Problem: Find Drivers with Improved Fuel Efficiency 🔗Problem Link: https://lnkd.in/gWqPXFQN 💡 Problem Breakdown: Identify drivers whose fuel efficiency improved: ✔ Calculate efficiency per trip (distance / fuel) ✔ Compare average efficiency between first half (Jan–Jun) and second half (Jul–Dec) ✔ Include only drivers with trips in both halves ✔ Compute improvement = second_half_avg - first_half_avg 34 days of consistent SQL practice completed ✅ Daily practice is turning concepts into intuition 💪 Let’s grow one query at a time 🚀 Drop your approach below 👇 #LeetCode #SQL #DataEngineering #Analytics #PerformanceAnalysis #SQLPractice #LearningInPublic #50DaysChallenge #DataAnalytics

❄️ LeetCode Daily Challenge 📅 Day 19 of 50 Days SQL Challenge Continuing my SQL journey with another Hard-level SQL problem focused on session analytics and behavioral anomaly detection. 📌 Problem: Find Zombie Sessions 🔗 Problem Link: https://lnkd.in/gDEr9VEq 💡 Problem Summary: We need to identify zombie sessions — sessions where users appear active but show abnormal behavior patterns. A session qualifies as a zombie session if it satisfies ALL conditions: ✔ Session duration > 30 minutes ✔ At least 5 scroll events ✔ Click-to-scroll ratio < 0.20 ✔ No purchases during the session Finally, return the result ordered by: scroll_count (DESC), session_id (ASC) The idea was to aggregate event-level data into session-level metrics, then filter sessions based on behavioral thresholds. Another Hard SQL challenge completed — consistency continues 💪 Let’s grow one query at a time 🚀 #LeetCode #SQL #DataEngineering #Analytics #Database #WindowFunctions #DailyPractice #LearningInPublic #50DaysChallenge

🚀 Day 25/50 of My #LeetCode SQL Challenge Today I solved “Product Sales Analysis III” 💡 This problem was about identifying the first year each product was sold and analyzing the corresponding sales data. 🔍 Key Learnings: How to identify the earliest occurrence of data within groups Strengthening concepts around data grouping and filtering Understanding how to extract meaningful insights from historical records 📊 Real-world relevance: This type of analysis is useful for: Tracking product launch performance Analyzing early sales trends Making data-driven business decisions ✨ Takeaway: Finding the first occurrence in data is a powerful technique that appears frequently in analytics and interviews. Consistency matters — one problem a day keeps improvement on track 💪 #Day25 #LeetCode #SQL #DataAnalytics #LearningInPublic #100DaysOfCode