Sep 8, 2025 · In SQL, UNION and UNION ALL are used to combine results from multiple SELECT statements. UNION returns only unique rows, whereas UNION ALL includes all rows, keeping …

Sep 8, 2008 · Both UNION and UNION ALL concatenate the result of two different SQLs. They differ in the way they handle duplicates. UNION performs a DISTINCT on the result set, …

Learn the difference between SQL UNION and UNION ALL with clear examples, when to use each, performance tips, and common pitfalls. Perfect for beginners and interview prep.

Jul 19, 2024 · The key difference is that UNION removes duplicate records, whereas UNION ALL includes all duplicates. This distinction not only changes the number of rows in the query …

Oct 1, 2025 · Discover the key differences between SQL's UNION and UNION ALL operators, their use cases, performance implications, and best practices for efficient queries.

Apr 26, 2025 · The UNION will combine two or more select statements to remove the duplicates, whereas the UNION ALL will not remove the duplicates but instead concatenate all the …

Jul 25, 2025 · Explore the fundamental distinctions between SQL's UNION and UNION ALL operators, including their impact on performance, duplicate handling, and data types.

Oct 15, 2025 · Understanding the differences between UNION and UNION ALL is important for writing optimized and reliable SQL queries. WHAT IS UNION? The UNION operator in SQL is …

Apr 13, 2025 · In SQL Server, UNION vs UNION ALL combines the result sets of two or more SELECT statements. While they may seem similar, they behave differently, especially …

UNION in SQL combines query results while removing duplicates, UNION ALL retains duplicates and performs faster. Learn the key differences.