Introduction To Database Questions and Answers

Answer: A

Correct answer: Tree structure

The hierarchical model organises records into a tree: every record type except the root has exactly one parent, and access is by navigating down from the root. That single-parent rule is its limitation - a many-to-many relationship cannot be represented without duplicating data - and it is what the network model, a “plex” or graph structure, was devised to relax.

Answer: C

Correct answer: Procedural query Language

Relational algebra is procedural: an expression specifies a sequence of operations - select, then project, then join - and so says how the result is to be obtained. Relational calculus and SQL are declarative by contrast.

Answer: C

Correct answer: foreign key

A foreign key is a column whose values must appear as a primary key in another table, and that requirement is what represents the relationship between the two. A primary key identifies rows within one table only.

Answer: B

Correct answer: All of these

A DBMS must do all three: protect data against a system crash, through logging and recovery; keep the stored information safe, through backup and integrity constraints; and restrict access to authorised users. These are among the central reasons for using a DBMS instead of ordinary files.

Answer: D

Correct answer: All of the above

All three are defining properties. A database is an integrated collection of logically related records; it consolidates what used to be separate files into a common pool; and the data in it is independent of the programs that use it, so the storage can change without rewriting the applications.

Answer: A

Correct answer: Data Definition Language

DDL comprises the statements that define and alter database structure, such as CREATE, ALTER and DROP. DML, the Data Manipulation Language, covers the statements that work on the rows themselves.

Answer: D

Correct answer: Database Management System

DBMS is Database Management System: the software that stores, retrieves, updates and administers the data, and enforces the rules that keep it consistent.

Answer: A

Correct answer: True

Before the database era, data was held in separate files, each written for one application, and largely on magnetic tape - which allows only sequential access. The consequences were duplicated data, inconsistency between files, and applications that broke whenever a file’s layout changed. Those problems are what databases were invented to solve.

Answer: C

Correct answer: a tuple

In relational terminology a row is a tuple, a column is an attribute, and the table as a whole is a relation.

Answer: C

Correct answer: data is integrated and can be accessed by multiple programs

The point of the database approach is that data is held once, in one place, and shared: many programs read the same integrated store instead of each keeping its own file. Redundancy falls rather than rises, and the data becomes independent of the programs.