Lectures

CASE WHEN expressions in SQL let you do if-else logic right inside your queries: you can classify values, handle NULLs, do calculations, and control how your data shows up. In this lecture, you'll learn how to use CASE to handle all sorts of situations you’ll run into in real tables.

Simple CASE form in SQL: how to use it as a compact switch-case replacement, for converting codes to text, visualizing statuses, and grouping. Examples, syntax, common mistakes, and comparison with searched CASE.

Learn how the GREATEST() and LEAST() functions work in PostgreSQL, how they interact with NULL, and how to avoid common mistakes when searching for max and min values in tables.

In this lecture, you'll learn how to handle NULL values in SQL in practice: sorting, filtering, replacing, and aggregating data with missing values. Real-world examples will help you get how to properly work with NULLs in reports and queries.

In this lecture, you'll learn about the most common mistakes when working with NULL in SQL: from wrong comparisons and unexpected results from aggregate functions to sorting quirks and foreign key gotchas. Forewarned is forearmed!