mysql check if null or 0 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: if column value is null then in mysql

SELECT 
    contactname, IFNULL(bizphone, homephone) phone
FROM
    contacts;