🧠 SQL Interview Question (Moderate & Analytical)
📌

events(user_id, event_name, event_date)

-- event_name values: 'Visited', 'Added_to_Cart', 'Purchased'

❓ Ques :

👉 Find users who added a product to cart but never completed the purchase.

🧩 How Interviewers Expect You to Think

• Understand funnel stage logic
• Apply conditional aggregation correctly
• Ensure absence of a specific event
• Avoid double counting users

💡 SQL Solution

SELECT
user_id
FROM events
GROUP BY user_id
HAVING
SUM(CASE WHEN event_name = 'Added_to_Cart' THEN 1 ELSE 0 END) > 0
AND SUM(CASE WHEN event_name = 'Purchased' THEN 1 ELSE 0 END) = 0;

🔥 Why This Question Is Powerful

• Tests real business thinking (conversion funnel analysis)
• Checks ability to detect missing conditions
• Common in product & e-commerce analytics interviews
• Evaluates aggregation + logical filtering skills together

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