The REPLACE syntax can be one of the following:
REPLACE [LOW_PRIORITY | DELAYED] [INTO] table_name [(field_name,...)] VALUES (expression,...),(...),... REPLACE [LOW_PRIORITY | DELAYED] [INTO] table_name [(field_name,...)] SELECT ... REPLACE [LOW_PRIORITY | DELAYED] [INTO] table_name SET field_name=expression, field_name=expression, ...
REPLACE is exactly like INSERT, except that when MySQL encounters a record with a primary or unique key that already exists, it will be deleted and replaced.