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Thursday, November 29, 2012

CS403 Fall 2011 old paper


CS403 Fall 2011

Question No: 1 ( Marks: 1 ) - Please choose one
Which one of the following E-R diagrams most correctly represents the relationship between Student and Grade entities?

Question No: 2 ( Marks: 1 ) - Please choose one
Which of the following statements are Data Definition Language command?
► INSERT
► UPDATE
► GRANT
► TRUNCATE

Question No: 3 ( Marks: 1 ) - Please choose one
Which of the following statements is true about the views?
► view is always a complete set of all the tables in a database
► View can not be used for retrieving data
► The results of using a view are not permanently stored in the database.
► Rows can not be updated or deleted in the view

Question No: 4 ( Marks: 1 ) - Please choose one
How many clustered index(es) do each database table have?
► 2
► 3
► 5
► 1

Question No: 5 ( Marks: 1 ) - Please choose one
Suppose there are 4 rows and 3 columns in TABLE1 and 6 rows and 5 coulmns in TABLE2; what is the size of the cartesian product incase of CROSS JOIN between these two tables?
► 24

► 20
► 18
► 15

Question No: 6 ( Marks: 1 ) - Please choose one
Which of the following is not one of the properties of Transaction?
► atomicity
► consistency
► redundancy
► durability



Question No: 7 ( Marks: 1 ) - Please choose one
Which of the following is INCORRECT about VIEWS?

► It is not possible to left out the data which is not required for a specific view.
► A database view displays one or more database records on the same page.
► Views can be used as security mechanisms
► Views are generally used to focus the perception each user
has of the database.


Question No: 8 ( Marks: 1 ) - Please choose one
Which of the following gives all the fields from employee table named as EMP?
► select * from EMP;
► select emp* from EMP'
► select emp_id where EMP;
► select * where EMP;

Question No: 9 ( Marks: 1 ) - Please choose one
Consider the relation Interview(CandidateNo, InterviewDate, InterviewTime, StaffNo, RoomNo) and the following functional dependencies.
FD1 : CandidateNo, InterviewDate -> InterviewTime, StaffNo, RoomNo
FD2 : RoomNo, InterviewDate, InterviewTime -> StaffNo, CandidateNo
FD3 : StaffNo, InterviewDate -> RoomNo
Which of the following is correct?
► The relation Interview is in 3NF
► The relation Interview is in BCNF.
► The FD3 violates 3NF.
► The FD2 violates 2NF.

Question No: 10 ( Marks: 1 ) - Please choose one
Which of the following types of partitioning reduces the chances of unbalanced partitions?

► Vertical
► List
► Hash
► Range
Hash Partitioning:
It is a type of horizontal partitioning. In this type particular algorithm is applied and
DBMS knows that algorithm. So hash partitioning reduces the chances of unbalanced
partitions to a large extent


Question No: 11 ( Marks: 1 ) - Please choose one
Which of the following is one of the purposes of using DDL commands?
► inserting records into databases
► updating records into databases
► manipulating databases
► creating and destroying databases


Question No: 12 ( Marks: 1 ) - Please choose one
Which of the following statements creates a database named COMPANY.

► CREATE DATABASE company
► CREATE DB company
► ADD DATABASE copmany
► CREATE company DATABASE


Question No: 13 ( Marks: 1 ) - Please choose one
What is the impact of setting multiple indexes for the same key, in index sequential files?

► Multiple indexes for the same key can not be set
www.vumba2009.blogspot.com

► It increases efficiency
► It decreases efficiency
► It will increase complexity as the access time will be increased

Question No: 14 ( Marks: 1 ) - Please choose one
Consider a transaction which includes following operations

Z= Z + 10
Write Z
...
Suppose that the value of Z after addition and the execution of this operation is 17. Now against the write operation the entry made in the log file will be
What does Z reflects in the above entry?
► Object being updated
► Identity of the transaction
► Object value
► Identity of the next transaction to be executed
In the entry, Tn reflects the identity of the transaction, Z is the object being updated
and 33 is the value that has to be placed in Z.


Question No: 15 ( Marks: 1 ) - Please choose one
Which of the following is not true regarding DB transactions?

► A set of database operations that are processed partly
A database transaction is a logical unit of database operations
► A database transaction must be atomic
► A database transaction must contains the ACID property


Question No: 16 ( Marks: 1 ) - Please choose one
Which of the following is not true about input forms?

► Provide an easy, effective, efficient way to enter data into a table
► Especially useful when the person entering the data is not familiar with the inner workings
► Provide different controls to add data into the tables
One input forms can populate one table at a time


Question No: 17 ( Marks: 1 ) - Please choose one
Which of the following is an example of volatile memory?

► RAM
► ROM
► Flash memory
► CPU

Question No: 18 ( Marks: 1 ) - Please choose one
Which of following is NOT generally the aim of data partitioning and placement of data?
► Reduce Workload
► Balance Workload
►merging different relations
► Speed up rate of useful works.

Question No: 19 ( Marks: 1 ) - Please choose one
ALTER TABLE exams
RENAME COLUMN Q_description TO Question_Descp, Std_ID to Student_ID.
Syntax of ALTER TABLE is NOT correct.
► True
False

Question No: 20 ( Marks: 1 ) - Please choose one
Which of the following is Advantage of Re-Hashing technique to handle the collisions?

► Collisions don’t use primary table space
► Unlimited number of elements
Fast access through use of main table space    (page29)
► Overhead of multiple linked lists


Question No: 21 ( Marks: 1 ) - Please choose one
Materialized views and Indexes are NOT similar by the following way(s).

► They consume storage space
► They must be refreshed when the data in their master tables changes.
► They can be accessed directly using a SELECT statement
► All of the Given
Unlike indexes, materialized views can be accessed directly using a SELECT statement.


Question No: 22 ( Marks: 1 ) - Please choose one
Select 'NORTH', CUSTOMER From CUST_DTLS Where REGION = 'N' Order By
CUSTOMER Union Select 'EAST', CUSTOMER From CUST_DTLS Where
REGION = 'E' Order By CUSTOMER
The above statement:
► Has an error - the string should be in double quotes.

► Has an error - ORDER BY clause.
► Does not have an error.
► Has an error - the string in single quotes 'NORTH' and 'SOUTH'.


Question No: 23 ( Marks: 1 ) - Please choose one
A software package designed to store and manage databases
► Database
► DBMS
► Data model
► Data


Question No: 24 ( Marks: 1 ) - Please choose one
Who is responsible for authorizing access to the database, for coordinating and monitoring its use ?
► Database Designers
► Database Administrators
► End Users
► Application Programmers


Question No: 25 ( Marks: 1 ) - Please choose one
A superkey that does not contain a subset of attributes that is itself a superkey is called a ____.
candidate key
► primary key
► superkey
► secondary key

Question No: 26 ( Marks: 1 ) - Please choose one
A ____ entity has a primary key that is partially or totally derived from the parent entity in the relationship.
► strong
► weak
► business
► relationship


Question No: 27 ( Marks: 2 )
What is the “data type”?

A data type in programming, a classification identifying one of various types of data, as floating-point, integer, or Boolean, stating the possible values for that type, the operations that can be done on that type, and the way the values of that type are stored.

Question No: 28 ( Marks: 2 )
Which DML statement changes the values of one or more columns based on some conditions.

Update command

Question No: 29 ( Marks: 2 )
Name the two types of caching that are commonly used in personal computers?
Two types of caching are commonly used in personal computers: memory
caching and disk caching

Question No: 30 ( Marks: 2 )
What is ‘Serial Execution’?

Serial execution is an execution where transactions are executed in a sequential order,
that is, one after another. A transaction may consist of many operations. Serial
execution means that all the operations of one transaction are executer first, followed
by all the operations of the next transaction and like that.

Question No: 31 ( Marks: 3 )
Write three benefits of using VIEWS.
They work as table and, provide security from unauthorized access.
updated automatically when some changes occurs in original table
views give a group of user’s access to just the information they are allowed to

Question No: 32 ( Marks: 3 )
Shortly explain BYTE data field?
Some of more frequently supported numeric data types include Byte, Integer, and Long Integer. Each of these types supports different range of numeric values and takes 1, 4 or 8 bytes to store. Now, if we declare the age attribute as Long Integer, it will definitely serve the purpose, but we will be allocating unnecessarily large space for each attribute. A Byte type would have been sufficient for this purpose since you won’t find students or employees of
age more than 255, the upper limit supported by Byte data type.

Question No: 33 ( Marks: 3 )
State the main purpose of index in relation with the queries executions.
It will help searching the required data by directly accessing it via index.

Question No: 34 ( Marks: 5 )
Differentiate between the cluster index and non cluster index ?
1 A cluster index is a form of tables which consist of column and rows.
2 Cluster index exists on the physical level
3 It sorts the data at physical level
4 It works for the complete table
5 There is a whole table in form of sorted data
6 A table can contain only one cluster index
Non Cluster Index
1 A non cluster index is in the form of a report about the tables.
2 They are not created on the physical level but at the logical level
3 It does not sort the data at physical level
4 A table has 255 non clustered indexes
5 A table has many non clustered indexes.
6 It work on the order of data

Question No: 35 ( Marks: 5 )
Consider the two relations,
Department (Dept_Code, Dep_Name,Dept_Head) and
Employee(Emp_ID,Emp_Name, Designation, DoB, Dept).
Write SQL statement to drop the primary key of Department relation? The fields in
Employee should reflect the removal in Department table.
Answer:
If you wanted to drop any Primary key column you first have to drop the primary key constraints and then you can drop the primary key column.
ALTER TABLE Department DROP CONSTRAINT Pkzxyx;
ALTER TABLE Department DROP COLUMN Dept_code;

Question No: 36 ( Marks: 5 )
Briefly explain rollback and roll forward.

There are two modes to database recovery, ROLLBACK and ROLLFORWARD. If a transaction amends, the user's transaction on the database is rolled back. ROLLBACK is the most common form of recovery.
The other form of database recovery is ROLLFORWARD. If a hard disk fails, then a ROLLFORWARD is performed to restore the database to the point in time of the disk failure. The logs are kept because they would need to be applied to a full backup of the database to restore the database to the point of disk failure.



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