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Create a SQL query to identify customers with purchases above a dynamic threshold.

SQLeasy0.5 min readPremium
Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Fragma Data Systems
Key Concepts Tested
sql
Expert AnswerPremium
91 wordsInterview-ready
**Architectural Logic**: Dynamic thresholds require subquery/CTE; efficiency depends on threshold computation. **Approach**: `WITH agg AS (SELECT customer_id, SUM(amount) AS total FROM purchases GROUP BY customer_id), threshold AS (SELECT percentile_cont(0.9) WITHIN GROUP (ORDER BY total) AS p90 FROM agg) SELECT a.* FROM agg a, threshold t WHERE a.total > t.p90`. **Why CTE**: Reusable threshold; single scan for percentile....
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