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Write a query to remove duplicate records from a table while retaining the earliest entry.

SQLmedium0.3 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
BCG
Key Concepts Tested
partition
Expert AnswerPremium
65 wordsInterview-ready
WITH ranked AS (SELECT *, ROW_NUMBER() OVER (PARTITION BY key_col1, key_col2 ORDER BY created_at ASC) AS rn FROM my_table) DELETE FROM my_table WHERE (key_col1, key_col2, created_at) IN (SELECT key_col1, key_col2, created_at FROM ranked WHERE rn > 1). **Why**: ORDER BY created_at ASC keeps earliest. For engines without CTE+DELETE: use temp table or MERGE....
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