Computer Science
Give the terms for each of the following:
(a) Collection of logically related records.
(b) DBMS creates a file that contains description about the data stored in the database.
(c) Attribute that can uniquely identify the tuples in a relation.
(d) Special value that is stored when actual data value is unknown for an attribute.
(e) An attribute which can uniquely identify tuples of the table but is not defined as primary key of the table.
(f) Software that is used to create, manipulate and maintain a relational database.