🧠 SQL Interview Question (Category Contribution % - Tricky)
📌

sales(category, product_id, revenue)

❓ Ques :

👉 For each category, calculate percentage contribution of each product’s revenue within that category

👉 Return category, product_id, revenue, contribution_percentage

🧩 How Interviewers Expect You to Think

• Calculate total revenue per category 📊
• Divide product revenue by category total
• Use window functions (SUM OVER)

💡 SQL Solution

SELECT
category,
product_id,
revenue,
(revenue * 100.0) / SUM(revenue) OVER (
PARTITION BY category
) AS contribution_percentage
FROM sales;

🔥 Why This Question Is Powerful

• Tests real business KPI calculation skills 🧠
• Evaluates understanding of window functions with aggregation
• Very common in Amazon, Flipkart, analytics roles

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