SQL-запрос: 

REPLACE INTO news( caption, news, text, avtor ) 
VALUES (
'ss', 'dd', 'ee', 'aa'
)
WHERE id = '2' 

Ответ MySQL:  
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE id='2'' at line 1