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128. View the Exhibits and examine the structures of the CUSTOMERS, SALES, and COUNTRIES tables.

You need to generate a report that shows all country names, with corresponding customers (if any) and sales details (if any), for all customers.

Which FROM clause gives the required result?

A. FROM sales JOIN customers USING (cust_id)

FULL OUTER JOIN countries USING (country_id);

B. FROM sales JOIN customers USING (cust_id)

RIGHT OUTER JOIN countries USING (country_id);

C. FROM customers LEFT OUTER JOIN sales USING (cust_id)

RIGHT OUTER JOIN countries USING (country_id);

D. FROM customers LEFT OUTER JOIN sales USING (cust_id)

LEFT OUTER JOIN countries USING (country_id);

Answer: C

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¼´ÊÇ×óÍâÁ¬½Ócustomers £¬ÏÔʾËùÓпͻ§£¬ÓÒÍâÁ¬½Ócountries £¬ÏÔʾËùÓÐ country names¡£