11、(5-8) choose the best answer:


Examine the structure of the BOOKS_TRANSACTIONS table.




You want to update this table such that BOOK_ID is set to 'INVALID' for all rows where no MEMBER_ID


has been entered.




Examine this partial SQL statement:


SQL> UPDATE books_transactions


SET book_id = 'INVALID'


WHERE...............


Which condition must be used in the WHERE clause to perform the required update?


A) MEMBER_ID = "";


B) MEMBER_ID IS NULL;


C) MEMBER_ID = NULL;


D) MEMBER_ID = '';




Answer:B


(解析:该题的题眼在“where no MEMBER_ID has been entered”)


09-09 23:52
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