Structure of the ORDERS table

Structure of the CUSTOMERS table
-Which of the following queries will return the same results as the following SQL statement? SELECT
A) SELECT customer#, lastname, firstname, order# FROM customers NATURAL JOIN orders;
B) SELECT customer#, lastname, firstname, order# FROM customers JOIN orders USING (customer#);
C) SELECT c.customer#, lastname, firstname, order# FROM customers c, orders o;
D) both a and b

Question

Structure of the ORDERS table
  
Structure of the CUSTOMERS table
-Which of the following queries will return the same results as the following SQL statement? SELECT
A) SELECT customer#, lastname, firstname, order# FROM customers NATURAL JOIN orders; 
B) SELECT customer#, lastname, firstname, order# FROM customers JOIN orders USING (customer#); 
C) SELECT c.customer#, lastname, firstname, order# FROM customers c, orders o; 
D) both a and b

Quizplus · Accepted Answer

Both queries use different syntax to achieve the same result of a join between the customers and orders tables, where the customer# and order# match. The NATURAL JOIN keyword in query A automatically matches columns with the same name in both tables, while query B uses the USING keyword to specify the column to join on. Both queries will return a resulting table with the columns customer#, lastname, firstname, and order#. Query C is incorrect as it performs a Cartesian product (all rows from both tables combined with each other) instead of a proper join.

Structure of the ORDERS Table