Author: Patrycja Dybka

-- -- -- -- -- We did it again! Each year, we review the SQL courses and tutorials on the market to help you find the best online resources to learn SQL. Find out which SQL courses are worth a try! But let's get to the point and take a closer look at some of the best online resources that can help beginners get started with SQL.

Usually we try to avoid NULLs, but sometimes we need to have a NULL instead of an actual value. When this need pops up, a helpful but little-known SQL function called NULLIF makes it possible. This post will introduce you to NULLIF and demonstrate its use in two example cases. In the article How to Tackle NULLS: The COALESCE Function , we got to know the COALESCE function. It returns the first not-null expression.