Author Question: The UNION of two relations A and B consists of all rows that are either in relation A or in relation ... (Read 67 times)

tingc95 · **on:** Jul 7, 2018

The UNION of two relations A and B consists of all rows that are either in relation A or in relation B or both.

Indicate whether the statement is true or false

Question 2

In database systems, the DBMS enforces rules about which user can perform which action when. The rules are known as ________.

A) referential integrity constraints
B) data modification control
C) data reading control
D) concurrency control