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答案解析：
显示所有客户的所有country names，对应的customers（如果有）和sales details（如果有）
即是左外连接customers ，显示所有客户，右外连接countries ，显示所有 country
names。