SELECT *
FROM table
WHERE YourColumn IS NOT NULL;
SELECT *
FROM contacts
WHERE last_name IS NULL;
SELECT IFNULL(NULL, "W3Schools.com");
IFNULL(MAX(EMAIL), "example@google.com") as email
SELECT
contactname, IFNULL(bizphone, homephone) phone
FROM
contacts;
SELECT * from TABLE where CODE IS NULL OR CODE!='C'