REPLACE is similar to INSERT command. The REPLACE command behaves as INSERT when there is no record matching the constraints. It still removes the existing records and again acts as INSERT, thereby providing the REPLACE effect. This might be handy in situations in which you do not want to worry about the exceptions during insertion.
CREATE TABLE `EMPLOYEE` ( `FIRSTNAME` VARCHAR(25) NOT NULL, `LASTNAME` VARCHAR(25) NOT NULL, PRIMARY KEY (FIRSTNAME, LASTNAME));REPLACE INTO EMPLOYEE (FIRSTNAME, LASTNAME) VALUES( 'Ray', 'Neil');/* Affected rows: 1 Found rows: 0 Warnings: 0 Duration for 1 query: 0.000 sec. */REPLACE INTO EMPLOYEE (FIRSTNAME, LASTNAME) VALUES( 'Ray', 'Neil');/* Affected rows: 1 Found rows: 0 Warnings: 0 Duration for 1 query: 0.000 sec. */ 
