Summary - NULL handling

Write NULL-safe queries with COALESCE and NULLIF.

In this group you learned NULL, IS NULL, COALESCE, NULLIF and IFNULL. Handling NULL correctly is key to robust queries.

SELECT COALESCE(NULLIF(total, 0), 1) AS duzelti FROM orders;

If total is 0 returns NULL then 1.

COALESCE(NULLIF(total, 0), 1) AS duzelti is selected from orders.

Exercise Summary - NULL handling

Select names from customers where email is null.

Show example solution

SELECT name
FROM customers
WHERE email IS NULL