insert if not exists or update mysql code example

Example 1: mysql insert exists update

INSERT INTO table (column_list)
VALUES (value_list)
ON DUPLICATE KEY UPDATE
   c1 = v1, 
   c2 = v2,
   ...;

Example 2: mysql insert into if not exists

INSERT INTO table_name (firstname, lastname)
SELECT 'NEW FIRSTNAME', 'NEW LASTNAME'
FROM DUAL
WHERE NOT EXISTS(
    SELECT 1
    FROM table_name
    WHERE firstname = 'NEW FIRSTNAME' AND lastname = 'NEW LASTNAME'
)
LIMIT 1;