Barney learns that the phone number for his friend Lacey in his ADDRESS_BOOK table has been disconnected; thus, her number is now unknown to him. Which SQL statement should Barney use to update the table so as to reflect this unknown value?
A) SELECT PHONE_NO FROM ADDRESS_BOOK WHERE (NAME = 'Lacey') SET NULL;
B) ALTER ADDRESS_BOOK SET PHONE_NO = NULL WHERE (NAME = 'Lacey');
C) UPDATE ADDRESS_BOOK SET PHONE_NO = 'NULL' WHERE (NAME = 'Lacey');
D) UPDATE ADDRESS_BOOK SET PHONE_NO = NULL WHERE (NAME = 'Lacey');

Question

Quizplus · Accepted Answer

To update a column value to NULL in SQL, the correct syntax is the UPDATE statement followed by the SET column name = NULL clause, where the condition to identify the correct row(s) to update is specified in the WHERE clause. Option D correctly follows this syntax to set Lacey's phone number to NULL.

Barney Learns That the Phone Number for His Friend Lacey