Question

Which of the following queries is valid?

A. SELECT b.title, b.retail, o.quantity
FROM books b NATURAL JOIN orders od
NATURAL JOIN orderitems o
WHERE od.order#=1005;
B. SELECT b.title, b.retail, o.quantity
FROM books orders.od, orderitems o
WHERE orders.order#=1005 = orderitems.order#
AND orderitems.isbn=books.isbn
AND od.order#=1005;
C. SELECT b.title, b.retail, o.quantity
FROM books b, orderitems 0
WHERE o.isbn = b.isbn
AND o.order#=1005;
D. None of the above

Answer 1

The valid query among the given options is A. SELECT b.title, b.retail, o.quantity FROM books b NATURAL JOIN orders od NATURAL JOIN orderitems o WHERE od.order#=1005;

Step-by-step explanation:

The valid query among the given options is A. SELECT b.title, b.retail, o.quantity FROM books b NATURAL JOIN orders od NATURAL JOIN orderitems o WHERE od.order#=1005;

This query joins three tables, books, orders, and orderitems, using the NATURAL JOIN keyword, which matches columns with the same name in these tables. It then selects the title, retail price, and quantity for a specific order with an order number of 1005.

Option B is invalid because it uses incorrect table aliases and an incorrect comparison condition. Option C is also invalid because it uses an invalid table alias and an incorrect column name in the WHERE condition.