Using REPLACE

The REPLACE statement is exactly like the INSERT statement except that if a key clash occurs, the new row you are inserting will replace the old row.

This is the general form of REPLACE from the MySQL manual:

REPLACE [LOW_PRIORITY | DELAYED]
[INTO] tbl_name [(col_name,...)]
VALUES (expression,...),(...),...

or REPLACE [LOW_PRIORITY | DELAYED]
[INTO] tbl_name [(col_name,...)]
SELECT ...

or REPLACE [LOW_PRIORITY | DELAYED]
[INTO] tbl_name
SET col_name=expression, col_name=expression,...

The similarity to INSERT should be obvious.