Database Management System Set 17

Database Management System

161.

Consider the following ER diagram dipicting the ralationship of an employee and supervisor:

Which is the possible relation if the above ERD is mapped into a relational model?

(a)	Employee(EmpID, BirthDate, Name(FirstName, MiddleName, LastName))
(b)	Employee(EmpID, BirthDate, Salary, Name(FirstName, MiddleName, LastName))
(c)	Supervision(EmpID, BirthDate, Salary, Name(FirstName, MiddleName, LastName), EmpID)
(d)	Supervisor(SupervisorID, BirthDate, Salary, Name(FirstName, MiddleName, LastName),EmpID), {EmpID})
(e)	Employee(EmpID, BirthDate, Salary, Name(FirstName, MiddleName, LastName),SupervisorID).

162.

Select the correct statement from among the following on proper naming of schema constructs:

(a)	Entity type name applies to all the entities belonging to that entity type and therefore a plural name is selected for entity type
(b)	In the narrative description of the database requirements, verbs tend to indicate the names of relationship types
(c)	The nouns arising from a database requirement description can be considered as names of attributes
(d)	Additional nouns which are appearing in the narrative description of the database requirements represent the weak entity type names
(e)	Adjectives written in the database requirement description help to identify the partial relationships among entities.

163.

Consider the following table obtained using Student and Instructor relations.

Which relational algebra operation could have been applied on the pair of relations Student and Instructor to obtain the above data?

164.

If k is a Primary key in a relation R1, then

(a)	Every tuple of R1 has a distinct value for K
(b)	K can have a null value for tuples in R1
(c)	K must be a key for some other relation
(d)	K is a foreign key for R1
(e)	K is a Composite key for R1.

165.

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

166.

What is data integrity?

(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)	All of the above.

167.

What are the most important advantages of the hirerchical database model?

(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.

168.

What is the logical description of the entire database showing all the data elements and relationships among them called?

169.

What is SQL?

(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.

170.

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

161.	e	Employee(EmpID, BirthDate, Salary, Name(FirstName, MiddleName, LastName),SupervisorID) is the possible relation if the given ERD is mapped into a relational data model.
162.	b	In the narrative description of the database requirements, verbs tend to indicate the names of relationship types.
163.	e	Instructor – Student is the relational algebra operation that could be applied on the pair of relations Student and Instructor to obtain the above data.
164.	a	If k is a primary key in relation R1, then it should be not contain duplicate value.
165.	d	Relational table database structure consists of a set of two or more related tables with a minimum of one shared field between them.
166.	d	Data integrity refers to maintaining consistency of the data in a database.
167.	E	The main important advantage of hierarchical data base model is conceptual ,simplicity, independence, integrity and efficiency.
168.	D	Schema describes the entire database and the logical description of the entire database is called conceptual schema.
169.	b	SQL is a data manipulation language used in relational DBMS.
170.	e	The subset of the specific data in the database which the user needs is called Subsechema.