SQL NULL Pitfalls: Why NOT IN Returns Zero Results and 3 Points Where MySQL and Oracle Behaviors Diverge

Introduction"I want to list customers who haven't ordered, but I get zero results," or "The count doesn't match when I ...

How to handle NULL (empty fields) and common pitfalls

For those new to data analysis, I will explain how to handle NULL (empty fields), where mistakes are most common in SQL, ...
Simon Fraser University

IS condition

IS NULL and IS MISSING are predicates that test for a missing value. IS NULL and IS MISSING are used in the WHERE, ON, and HAVING expressions. Each predicate resolves to true if the sql-expression's ...