Database Management System Set 15

Database Management System

Questions  141 to 150

141.	How a null value is created or represented? (a) A zero (b) A space (c) Entering a value (d) Pressing the Enter key without making a prior entry of any kind (e) Pressing the ESC key.
142.	What does a multi level index lead to? (a) Binary Tree (b) B-tree (c) Mapping (d) Transaction Failure (e) Dead Lock.
143.	Select the incorrect statement describing the keys used in a Relational Data Model. (a) A primary key is an attribute that uniquely identifies each row in a relation (b) A composite key is a primary key that consists of more than one attribute (c) A foreign key can be an attribute in a relation of a database that draws values from the same domain as a primary key of another relation in the same database (d) Candidate key is an attribute that uniquely identifies a column in a relation (e) One field or combination of fields for which more than one record may have the same combination of values is called the secondary key.
144.	Choose the Suitable example for derived attribute from the following: (a) Roll no (b) Name (c) Marks (d) Age (e) Phone number.
145.	Which clause is used to produce a list of only values that are different from one another? (a) Aggregate (b) Restricted (c) Select (d) Distinct (e) Group By.
146.	What is the maximum height of a B+-tree of order m with n key values? (a) M (b) long m/2  n/2 (c) long m n (d) log n m (e) log  m/2 (n/2) + 1.
147.	Which set of operators represents the complete set for relational algebra? (a) Union, Difference, Projection, Selection, Cartesian Product (b) Selection, Cartesian Product, Projection, Union, Intersection (c) Cartesian Product, Projection, Selection, Difference, Intersection (d) Join, Union, Projection, Selection, Difference (e) Difference, Projection, Selection, Join, Intersection.
148.	Which of the following RAID level is also called a rotating parity array? (a) 1 (b) 2 (c) 5 (d) 4 (e) 0.
149.	Fill in the blanks by selecting the correct option(s) given below: “In a relational data model, the columns of a table are called  and the rows are called tuples.  The primary key index does not allow data in a field. Views has characteristics of tables and can be used for .” (a) (i)  keys          (ii) multiple                       (iii) queries (b) (i)  fields        (ii) enter                           (iii) reports (c) (i)  fields        (ii) duplicate         (iii) queries (d) (i)  data          (ii) enter                           (iii) form (e) (i)  attributes   (ii) duplicate         (iii) reports.
150.	What storage device can be used to create an index sequential file? (a) ISAM (b) Direct Access (c) Sequential access (d) Tape (e) Hashed.

Answers

141.	Answer : (a) Reason:  Composite attribute that can be further subdivided to yield additional attributes
142.	Answer : (d) Reason:  A null value is created or represented by pressing the Enter key without making a prior entry of any kind.
143.	Answer : (d) Reason:  Distinct clause is used to produce a list of only values that are different from one another
144.	Answer : (a) Reason:  Atomicity property of transaction ensures that either all operations of the transaction are reflected properly in the database or none.
145.	Answer : (b) Reason:  Hashed type of file is easiest to update.
146.	Answer : (e) Reason:  Having states the condition for Group Selection
147.	Answer : (d) Reason:  Two phase lock   procedure is used for acquiring the necessary locks for a transaction where all necessary locks are acquired before any are released
148.	Answer : (b) Reason:  Employees, Customers, Account, Vehicle  are examples of Entities.
149.	Answer : (d) Reason:  Age is the derived attribute
150.	Answer : (c) Reason:  RAID level 5  is also called a rotating parity array

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