What is NULL?

Learn that NULL represents an unknown value.

NULL means an unknown or missing value. It is not zero or empty text; it is the absence of a value.

SELECT name FROM customers
WHERE email IS NULL;

This query finds customers whose email was not entered.

name is selected from customers. WHERE keeps only the rows where email IS NULL holds.

What is NULL? — details

Arithmetic with NULL gives NULL. Even NULL = NULL is not true; always check with IS NULL.

Select names from customers where email is null.

Show example solution

SELECT name
FROM customers
WHERE email IS NULL

Null check

SELECT name FROM customers
WHERE email ____;

Show answer

SELECT name FROM customers
WHERE email IS NULL;

Next lesson: IS NULL