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Write a SQL query to detect customers who have not placed a second order in 90 days.

SQLmedium0.3 min readPremium

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56 wordsInterview-ready

SELECT customer_id FROM (SELECT customer_id, order_date, LAG(order_date) OVER (PARTITION BY customer_id ORDER BY order_date) AS prev_order, DATEDIFF(order_date, LAG(order_date) OVER (...)) AS days_since_prev FROM orders) t WHERE prev_order IS NOT NULL AND days_since_prev > 90. **Why**: LAG gives previous order date; DATEDIFF to gap. Refine per definition of "second order" (e.g., first repeat)....

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