COALESCE() / IFNULL()
function
COALESCE returns the first non-NULL value; IFNULL returns alt if expr is NULL.
Syntax
COALESCE(val1, val2, ...) IFNULL(expr, alt)
Example
sql
-- Use default if null
SELECT COALESCE(phone, mobile, 'N/A') AS contact FROM users;
SELECT IFNULL(bio, 'No bio provided') AS bio FROM profiles;
-- Useful in aggregates
SELECT SUM(COALESCE(discount, 0)) FROM orders;