Have you ever needed to combine data from two different tables or queries in SQL Server? Maybe you’ve got similar data sitting in different places and you want to see all the unique values, or maybe you want to see everything, even the repeats. UNION and UNION ALL come into play here. Both are handy tools for stacking the results of two or more SELECT statements on top of each other, but they handle repeats differently.
In this article, we’ll walk through what makes them different, using simple examples to keep things clear and easy to follow. Let’s dive in