How do you write a SQL query to find duplicate records in a table and how do you remove them?
This question tests your ability to identify duplicate rows in SQL and remove them safely. A common approach is to use <code>GROUP BY</code> with <code>HAVING COUNT(*) > 1</code> to detect duplicate business keys, then use a window function such as <code>ROW_NUMBER()</code> to rank rows within each group and delete every row except the one you want to keep. In a strong answer, you should also explain the retention rule clearly, such as keeping the smallest <code>id</code> or the newest timestamp.
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