UNION vs UNION ALL SQL Operators

Date: 2023-01-02

This tutorial compares SQL's UNION and UNION ALL operators using PostgreSQL. UNION combines result sets, removing duplicates, while UNION ALL combines them, retaining duplicates. The tutorial demonstrates their use with example queries on a sample database, set up conveniently using Docker. The key difference lies in duplicate handling; UNION is slower due to this extra processing. Downloadable SQL scripts are provided.

Read more: https://examples.javacodegeeks.com/union-vs-union-all-sql-operators/