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Which SQL clause is used to combine the result sets of two or more SELECT statements?
- JOIN
- MERGE
- UNION
- COMBINE
Answer: UNION
UNION combines result sets of multiple SELECT queries into a single result, removing duplicates by default. UNION ALL retains duplicates and is faster. Requirements: same number of columns, compatible data types, and same column order. Useful for consolidating data from similar tables or partitioned datasets.