Question

Which of the following queries will display data from both the ORDERS and CUSTOMERS tables?

a) SELECT * FROM ORDERS, CUSTOMERS
b) SELECT * FROM ORDERS JOIN CUSTOMERS
c) SELECT * FROM ORDERS INNER JOIN CUSTOMERS
d) SELECT * FROM ORDERS CROSS JOIN CUSTOMERS

Answer 1

To display data from both ORDERS and CUSTOMERS tables, an INNER JOIN is typically used with a condition to match rows. A query like 'SELECT * FROM ORDERS INNER JOIN CUSTOMERS' would be structurally correct but requires a joining condition to function properly.

Step-by-step explanation:

The query that will display data from both the ORDERS and CUSTOMERS tables depends on the nature of the relationship between these tables. Options a), b), and d) will result in a Cartesian product, wherein each row from the ORDERS table is combined with each row from the CUSTOMERS table, which is usually not the desired outcome unless explicitly intended. On the other hand, option c) SELECT * FROM ORDERS INNER JOIN CUSTOMERS implies that there should be a condition specified on how the tables are to be joined (typically on matching columns in both tables), thereby producing a result set that includes rows with matching values in both tables. Without additional context or a ON clause to specify the joining condition, options b) and c) are incomplete SQL statements and will result in an error.