List of lectures for the course SQL, 9 quest level on JavaRush

Getting to Know NULL. How NULL is Different from 0
SQL SELF
9 level,0 lecture
In this lecture, you'll find out what the NULL value is in SQL, how it's different from zero and an empty string, how to work with it, and why it's such a big deal in databases. We'll break down with examples how NULL affects calculations, conditions, and aggregate functions.
Open
Checking NULL Values: IS NULL and IS NOT NULL
SQL SELF
9 level,1 lecture
Learn how to properly check for NULL values in SQL using the IS NULL and IS NOT NULL operators, so you can filter, analyze, and handle data with missing values.
Open
How NULL Affects Aggregate Functions: SUM(), COUNT(), AVG(), MIN(), MAX()
SQL SELF
9 level,2 lecture
Find out how NULL values impact aggregate functions in SQL: SUM, COUNT, AVG, MIN, MAX. We'll break it down with examples, see how these functions behave when there's missing data, and learn how to dodge common mistakes when analyzing tables with NULLs.
Open
Handling NULLs in Calculations with COALESCE()
SQL SELF
9 level,3 lecture
Learn how to use the COALESCE() function to handle NULL values in SQL: examples, syntax, common mistakes, and practical tips.
Open
The NULLIF() Function — Syntax and Usage Examples
SQL SELF
9 level,4 lecture
Check out the NULLIF() function in PostgreSQL: syntax, hands-on examples, and use cases for handling NULL values, avoiding division by zero errors, filtering data, and making your SQL queries easier to read.
Open