Comparison data of different types is a complex topic. Final results are different for different languages. Today, my co-worker René noticed "interesting" behavior for comparison in SQL. It's so interesting that I've decided to share it with you :)

In this article, I want to show you queries might sometimes return results which may look strange at first glance. You need to remember the devil is in the detail while creating queries 😈

UNION and UNION ALL are very similar - both combines result-set of SELECT queries, but the final sets are different. Let me allow to show you differences.