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Write a SQL query to remove duplicates from a table.

SQLmedium0.4 min readPremium

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DELETE keeping one: DELETE FROM t WHERE id NOT IN (SELECT MIN(id) FROM t GROUP BY col1, col2). Or temp: CREATE TABLE t_dedup AS SELECT DISTINCT ON (col1, col2) * FROM t. Or ROW_NUMBER: WITH ranked AS (SELECT *, ROW_NUMBER() OVER (PARTITION BY key_cols ORDER BY tie_breaker) rn FROM t) DELETE FROM t WHERE (id) IN (SELECT id FROM ranked WHERE rn > 1). **Best**: MERGE or INSERT into new table with dedup....

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