sql server return 0 if null code example

Example 1: mysql return 0 if null

SELECT IFNULL(field, 0) AS field FROM products WHERE id = 1

SELECT IFNULL(SUM(field), 0) as field FROM products

Example 2: sql is not null

The reverse of NULL. Tests for values that aren’t empty / NULL
"Tests for empty (NULL) values.
Example: Returns users that haven’t given a contact number.
SELECT * FROM users
WHERE contact_number IS NULL;"