SQL: NULL Values & CASE Expressions

Understand one of the most common sources of wrong answers in SQL: NULL. This course explains what NULL means, why comparisons with NULL behave unexpectedly, how NULLs affect counts, sums and joins, and how to handle them with IS NULL, COALESCE, NULLIF and CASE expressions.

Tutwoo is an independent learning provider. This course is general skills training based on official documentation. It is not an accredited qualification. Software behaviour can change between versions, so check the official documentation for the version you use.