Tag: Exists

Spooky Scary NULL: Unexpected Danger Lurking in Your Database

NULL, NOT NULL,
Relational databases often store the value NULL in their tables. If you’re not familiar with NULL and what it is, you could run into unexpected problems. In this article, we’ll take a look at how the IN and EXISTS operators work with NULL. What Is NULL? In SQL, NULL is a special value indicating that a particular piece of data doesn’t exist in the database. For SQL beginners, it’s often a source of problems.