Database Management System (DBMS) 01

1. If a relation with a Schema R is decomposed into two relations R1 and R2 such that (R1 ∪ R2) = R1 then which one of the following is to be satisfied for a lossless joint decomposition (→ indicates functional dependency)     [Paper III December 2012]
(A) (R1 ∩ R2) → R1 or R1 ∩ R2 → R2
(B) R1 ∩ R2 → R1
(C) R1 ∩ R2 → R2
(D) R1 ∩ R2 → R1and R1 ∩ R2 → R2

2. Which level of Abstraction describes how data are stored in the data base?
                                                                                                 [Paper III December 2012]
(A) Physical level
(B) View level
(C) Abstraction level
(D) Logical level

3. Third normal form is based on the concept of ______. [Paper III December 2012]
(A) Closure Dependency
(B) Transitive Dependency
(C) Normal Dependency
(D) Functional Dependency

4. Referential integrity is directly related to                              [Paper III December 2012]
(A) Relation key
(B) Foreign key
(C) Primary key
(D) Candidate key

5. The SQL Expression Select distinct T. branch name from branch T, branch S where T. assets > S. assets and S. branch-city = DELHI, finds the name of                        [Paper II December 2011]

(A) all branches that have greater asset than any branch located in DELHI.

(B) all branches that have greater assets than allocated in DELHI.

(C) the branch that has the greatest asset in DELHI.

(D) any branch that has greater asset than any branch located in DELHI.

6. What is Granularity ?                                                         [Paper III June 2012]

(A) The size of database

(B) The size of data item

(C) The size of record

(D) The size of file

7. Match the following:                                                         [Paper III June 2012]

(i) OLAP                     (a) Regression

(ii) OLTP                     (b) Data Warehouse

(iii) Decision Tree        (c) RDBMS

(iv) Neural Network    (d) Classification

(i)         (ii)        (iii)       (iv)

(A)       (b)        (c)        (a)        (d)

(B)       (b)        (c)        (d)       (a)

(C)       (c)        (b)        (a)        (d)

(D)       (c)        (b)        (d)       (a)

8. The problem that occurs when one transaction updates a database item and then the transaction fails for some reason is ________.                                                    [Paper III June 2012]

(A) Temporary Select Problem

(B) Temporary Modify Problem

(C) Dirty Read Problem

(D) None

9. Consider a schema R(A, B, C, D) and functional dependencies A →B and C →D.

Then the decomposition R1(A, B) and R2(C, D) is               [Paper III June 2012]

(A) Dependency preserving but not lossless join

(B) Dependency preserving and lossless join

(C) Lossless Join but not dependency preserving

(D) Lossless Join

10. In multiuser database if two users wish to update the same record at the same time, they are prevented from doing so by           [Paper II June 2012]

(A) Jamming                        (B) Password

(C) Documentation              (D) Record lock

SOLUTIONS

1. A

2. A
Three levels of data abstraction are:
a. Physical level : How the data is stored physically and where it is stored in database.
b. Logical level : What information or data is stored in the database (like what is the datatype or what is format of data).
c.View level : end users work on view level. It describes the part of data visible for each user

3. B

4. B
For referential integrity to hold in a relational database, any field in a table that is declared a foreign key can contain only values from a parent table's primary key or a candidate key.
Referential integrity is a database concept that ensures that relationships between tables remain consistent. When one table has a foreign key to another table, the concept of referential integrity states that you may not add a record to the table that contains the foreign key unless there is a corresponding record in the linked table.

5.

6.

7.

8.

9.

10.