Database Management System Set 19

Database Management System

181.

Which of the following database structure consists of a set of two or more related tables with a minimum of one shared field between them?

182.

Which of the following include guidelines for creating tables in a relational database?

(a)	Only one table in the database needs a primary key
(b)	The primary key need not be unique
(c)	Attributes may appear in several tables
(d)	Data must be atomic.
(e)	The secondary key need to be unique.

183.

Data integrity refers to

(a)	The inability to view a database because of system problems
(b)	Data being unavailable because it is being used by another user
(c)	Maintaining consistency of the data in a database
(d)	Preventing disclosure of information that causes harm
(e)	The ability to view a database because of system problems.

184.

The most important advantages of the hierarchical database model is/are

(a)	Conceptual simplicity, integrity, diversity and security
(b)	Security, efficiency, diversity, simplicity and integrity
(c)	Integrity, efficiency, diversity, independence and simplicity
(d)	Conceptual simplicity, security, hierarchy
(e)	Conceptual simplicity, security, independence, integrity and efficiency.

185.

The data hierarchy which goes from bits and bytes to

(a)	Entities, attributes, fields and records
(b)	Fields, attributes, entities and records
(c)	Fields, records, files and databases
(d)	Records, entities, fields and databases
(e)	Attributes, entities, records and tuples.

186.

What is the Duplicate data in multiple data files called?

(a)	Data redundancy
(b)	Always necessary in networked databases
(c)	Typical of the relational model
(d)	A characteristic of a hierarchy
(e)	Data dictionary.

187.

The logical description of the entire database showing all the data elements and relationships among them called

188.

The specific set of data from the database that is required by each user or application program called

189.

SQL is

(a)	A first-generation language
(b)	The standard data manipulation language for relational DBMS
(c)	The query language used for networked databases
(d)	Never used for reports
(e)	A natural language approach to gathering information from databases.

190.

The basic SQL aggregate function that gives the number of rows containing not null values for the given column is

181.	Answer : (d) Reason : A relational database consists of two or more related tables.
182.	Answer : (d) Reason : For the database to function efficiently, data must be atomic
183.	Answer : (c) Reason : Data integrity refers to maintaining consistency of the data in a database.
184.	Answer : (e) Reason : The main important advantage of hierarchical data base model is conceptual ,simplicity, independence, integrity and efficiency.
185.	Answer : (e) Reason : Set of fields make up a record, set of records will make a files .
186.	Answer : (a) Reason : duplication of data is called redundancy.
187.	Answer : (d) Reason : Schema describes the entire database and the logical description of the entire database is called conceptual schema.
188.	Answer : (e) Reason : The subset of the specific data in the database which the user needs is called Subsechema.
189.	Answer : (b) Reason : SQL is a data manipulation language used in relational DBMS.
190.	Answer : (b) Reason : Count function gives the number of rows containing not null values for the given column.