Working with NULLs

NULL Basics

NULL means "no value" or "unknown". It's different from empty string or zero.

Testing for NULL

-- Correct way:
WHERE phone IS NULL
WHERE phone IS NOT NULL
-- WRONG (doesn't work):
WHERE phone = NULL

Your Task

Find leads with missing phone numbers:

• Show: id, first_name, last_name, phone
• Where phone IS NULL
• Order by id