July 2016 - Paper 2

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3. July 2016
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16:  

In RDBMS, the constraint that no key attribute (column) may be NULL is referred to as :

A.	Referential integrity
B.	Multi-valued dependency
C.	Entity Integrity
D.	Functional dependency
	Answer Report Discuss
	Option: C Explanation : Click on Discuss to view users comments. Write your comments here: Updating your Comments.. Updating your Comments..

17:  

Which of the following statement(s) is/are FALSE in the context of Relational DBMS ?

 

I. Views in a database system are important because they help with access control by allowing users to see only a particular subset of the data in the database.

 

II. E-R diagrams are useful to logically model concepts.

 

III. An update anomaly is when it is not possible to store information unless some other, unrelated information is stored as well.

 

IV. SQL is a procedural language.

A.	I and IV only
B.	III and IV only
C.	I, II and III only
D.	II, III and IV only
	Answer Report Discuss
	Option: D Explanation : Click on Discuss to view users comments. Write your comments here: Updating your Comments.. Updating your Comments..

18:  

In a relational database model, NULL values can be used for all but which one of the following ?

A.	To allow duplicate tuples in the table by filling the primary key column(s) with NULL.
B.	To avoid confusion with actual legitimate data values like 0 (zero) for integer columns and ’’ (the empty string) for string columns.
C.	To leave columns in a tuple marked as ’’unknown’’ when the actual value is unknown.
D.	To fill a column in a tuple when that column does not really ”exist” for that particular tuple.
	Answer Report Discuss
	Option: A Explanation : Click on Discuss to view users comments. Write your comments here: Updating your Comments.. Updating your Comments..

19:  

Consider the following two commands C1 and C2 on the relation R from an SQL database :

 

C1 : drop table R;

 

C2 : delete from R;

 

Which of the following statements is TRUE ?

 

I. Both C1 and C2 delete the schema for R.

 

II. C2 retains relation R, but deletes all tuples in R.

 

III. C1 deletes not only all tuples of R, but also the schema for R.

A.	I only
B.	I and II only
C.	II and III only
D.	I, II and III
	Answer Report Discuss
	Option: C Explanation : Click on Discuss to view users comments. Write your comments here: Updating your Comments.. Updating your Comments..

20:  

Consider the following database table having A, B, C and D as its four attributes and four possible candidate keys (I, II, III and IV) for this table :

 

I : {B} II : {B, C} III : {A, D} IV : {C, D}

 

If different symbols stand for different values in the table (e.g., d1 is definitely not equal to d₂), then which of the above could not be the candidate key for the database table ?

A	B	C	D
a1	b1	c1	d1
a2	b3	c3	d1
a1	b2	c1	d2

 

A.	I and III only
B.	III and IV only
C.	II only
D.	I only
	Answer Report Discuss
	Option: C Explanation : Click on Discuss to view users comments. Write your comments here: Updating your Comments.. Updating your Comments..

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