Answer to Question #238087 in Databases | SQL | Oracle | MS Access for Owen

Question

2.3.1 Which query can produce a contrasting answer? Give the simplest database instance you can think of where a different answer is produced.

Answer 1

The query that produces contrasting answers is query c. For example, let M={(3, 4)} and N = {(1, 2)}. Query c will produce {(3, 2)} while query a and b produces an empty result.