6. SQL 語法 UPDATE 之正確寫法為何？
(A)UPDATE bookname FROM Books WHERE id = 2 SET bookname ='哈利波特'
(B)UPDATE FROM Books WHERE id = 2 SET bookname = '哈利波特'
(C)UPDATE Books WHERE id = 2 SET bookname = '哈利波特'
(D)UPDATE Books SET bookname = '哈利波特' WHERE id = 2。