Describe the GRANT function and explain, how it associates to security. What kind of privileges may be granted? How are they revoked?

Ans: Since more than one user can aaccess one database, there exists the required to restrict user from using whole database in any way. Setting up access privilege can do this. Any privilege can be granted to or revoked from user along with taken of the GRANT and REVOKE statements. Each privilege could be granted or revoked individually or in a group. Such group of rights is known as ROLE and rights can be granted or revoked within in the similar way as to the user. Access privileges include SELECT, INSERT, UPDATE and DELETE.

GRANT {statement|role_name} ON {object_name} TO {user|role_name_2} [WITH GRANT OPTION]

An example of granting permission to user B for reading EMP table is:

GRANT SELECT ON emp to B;

The REVOKE statement is used to revoke the permissions from the user.
The syntax for REVOKE statement is given as:
REVOKE {statement|role_name} FROM {user|role_name};