Fundamentals of Database Systems questions and answers with explanation for fresher's and experienced for interview, competitive examination and entrance test.

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PART I – Single and Multiple choices:
1) The common types of entities are:
 Strong entities  Weak entities
 Associative entities  All of the above
2) The logical representation of an organization's data is called a(n):
 Database model  Entity-relationship model
 Relationship systems design  Database entity diagram
3) Customers, cars, and parts are examples of:
 Entities  Attributes
 Cardinals  Relationships
4) An entity type whose existence depends on another entity type is called a(n) _____
entity.
 Strong  Weak
 Codependent  Variant
5) A(n) _____ is the relationship between a weak entity type and its owner.
 Member chain  Jump path
 Chain link  identifying relationship
6) A property or characteristic of an entity type that is of interest to the
organization is called a(n):
 Attribute  Coexisting entity
 Relationship  Cross-function
7) A person's name, birthday, and social security number are all examples of:
 Attributes  Entities
 Relationships  Descriptors
8) An attribute that can be broken down into smaller parts is called a(n) _____
attribute.
 Associative  Simple
 Composite  Complex

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9) The following figure shows an example of:
 A composite attribute  A relational attribute
 A derived attribute  A multivalued attribute
10) An attribute that can be calculated from related attribute values is called a(n)
_____ attribute.
 Simple  Composite
 Multivalued  Derived
11) The total quiz points for a student for an entire semester is a(n) _____
attribute.
 Derived  Mixed
 Stored  Addressed
12) Which of the following criteria should be considered when selecting an identifier?
 Choose an identifier that is stable
 Choose an identifier that will not be null
 Choose an identifier that doesn’t have large composite attributes
 All of the above
13) Which of the following conditions should exist if an associative entity is to be
created?
 All the relationships for the participating entities are many-to-many
 The new associative entity has independent meaning
 The new associative entity participates in independent relationships
 All of the above

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14) The number of entity types that participate in a relationship is called the:
 Number  identifying characteristic
 Degree  Counter
15) A relationship between the instances of a single entity type is called a(n) _____
relationship.
 Ternary  Primary
 Binary  Unary
Part II - Basic Terms and Data Model:
1) Persons can take the following roles around database systems:
 End users
 DB designers
 DB administrators
 Application Programmers
Decide for each of the following activities, to which role it belongs by writing
the respective number in the box.
 Developing the conceptual schema

Managing user accounts, hardware resources, and backups during the
lifetime of the database
 Programming of software that is using the database
 Choice of DBMS
 Analyze requirements for the database
 Programming of a graphical user interface for the database
 Gathering of information about the application field

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2) Classification of Database Management Systems:
a) Name three different data models that can be used in DBMS:
Relational Model Object Relational Model Network Model
b) Which data model is used by MySQL?
Relational Model
c) Is MySQL a single-user or a multi-user DBMS?
Multi-User
Part III – ER to Relational Mapping:
1) Name and explain in brief (just briefly), the steps that are needed to transform an
ER diagram into a relational schema.
1. Mapping Strong Entities
2. Mapping Weak Entities
3. Mapping One-to-One relationship
4. Mapping One-to-Many relationship
5. Mapping Many-to-Many relationship
6. Mapping Multi-Valued attributes
7. Mapping N-ary relationship

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Part IV – Challenges:
1) You have the following two figures. Both using the one-to-many relation but in
different ways. Are they the same? Yes / No, Give reason.
Using the above "One-to-Many" relationship the implementation is simple and easy;
but support one depth and level of relationship, as for instance, a sub-forum can't
have other sub-forums!
Using the above recursive relationship it supports both one level and as many level
as possible of nested relationships. For instance, a forum can have a sub-forum;
the sub-forum still can have other sub-forums and yet that other sub-forums can
have sub-forums and so on, so forth.
2) There is something wrong with the following query (The problem is the single
quotation-marks with the string). Try to rewrite it with correct syntax using two
different methods.
SELECT * FROM lecturers WHERE signatory = 'If you tell the truth,
you don't have to remember anything';
 SELECT * FROM lecturers WHERE signatory = "If you tell the truth, you don't
have to remember anything";
 SELECT * FROM lecturers WHERE signatory = 'If you tell the truth, you don't
have to remember anything';
Forum Sub Forumhas
1 m
Forum
has
1 mmain
sub
Figure 1 - One-to-Man
Figure 2 - Recursive

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‫آکعیَض‬02‫یک‬‫اًجوي‬‫غیر‬‫اًتفاعی‬‫تا‬‫ّذف‬‫تمَیت‬ ٍ‫تغییر‬‫پرٍرغ‬ ٍ ‫آهَزغ‬‫طریك‬ ‫از‬ِ‫ارائ‬‫آهَزغ‬ٍ‫کوک‬ِ‫ت‬
‫هتخصصاى‬‫علَم‬‫کاهپیَتر‬‫اظت‬.
‫ایي‬ ‫ًام‬‫اًجوي‬‫پر‬ َ‫آه‬ ‫دریای‬ ‫از‬ ِ‫ترگرفت‬‫آى‬ ‫هَج‬ ‫دظت‬ ِ‫ک‬ ًِ‫هیا‬ ‫آظیای‬ ‫رٍد‬ ‫تریي‬ ‫آب‬‫تیاًگر‬‫اظتعذاد‬‫ایي‬ ِ‫ًْفت‬ ‫ّای‬‫اًجوي‬ُ‫تَد‬،‫از‬ ‫دریا‬ ‫ایي‬ ٍ
‫هاٍرای‬ ٍ ِ‫گرفت‬ ِ‫ظرچؽو‬ ‫پاهیر‬ ‫کْي‬ ‫ّای‬ ٌِ‫داه‬‫خذهات‬ ِ‫ارای‬ ‫ّذف‬ ‫دریا‬ ‫حالت‬ ‫ایي‬ ِ‫ک‬ ‫هیکٌذ‬ ‫آتیاری‬ ‫را‬ ‫افغاًعتاى‬ ‫تاظتاًی‬ ‫ظرزهیي‬ ‫ؼوالی‬
‫اًجوي‬‫اًعکاض‬ ‫را‬.‫هیذّذ‬
‫آکعیَض‬02‫هاًٌذ‬ ‫خذهاتی‬ ‫تا‬ ‫دارد‬ ‫ًظر‬ ‫در‬‫ایجاد‬‫فضای‬‫علوی‬ ‫ؼکَفایی‬ ٍ ‫خاللیت‬ ‫تراًگیختي‬ ٍ ‫اظتعذادّا‬ ‫تجلی‬ ‫ترای‬ ‫هٌاظة‬‫داًػ‬ ٍ ‫هحصالى‬
،‫پصٍّاى‬ٍ ‫علوی‬ ِ‫ترًاه‬ ‫فَق‬ ‫ّای‬ ‫فعالیت‬ ‫ظاختي‬ ‫ًْادهٌذ‬،‫کارتردی‬‫ؼٌاظایی‬‫عاللوٌذ‬ ٍ ِ‫ًخث‬ ،‫خالق‬ ‫افراد‬‫در‬ ‫آًْا‬ ‫هؽارکت‬ ‫از‬ ‫گیری‬ ُ‫تْر‬ ٍ
‫علوی‬ ‫فضای‬ ‫ارتمای‬ٍ ‫تَلیذ‬ ‫ّوچَى‬ ِ‫جاهع‬ ٍ ‫آهَزؼی‬ ‫هراکس‬ ‫دیگر‬ ٍ ‫ّا‬ ‫پٌَّتَى‬‫تخصصی‬ ‫علوی‬ ‫ًؽریات‬ ‫اًتؽار‬‫تکٌالَشی‬ ٍ ‫عصری‬ ‫علَم‬
‫هَثر‬ ‫ؼکل‬ ِ‫ت‬ ‫را‬ ‫هعلَهاتی‬ِ‫جاهع‬ ‫افراد‬ ‫آهال‬ ِ‫ت‬ ‫رظیذى‬ ‫ّای‬ ُ‫را‬ ٍ ‫پصٍّػ‬ ٍ ‫تحمیك‬ ،‫تذریط‬ ٌِ‫زهی‬ ‫ؼذى‬ ‫تْتر‬ ِ‫ّرچ‬ ‫راظتای‬ ‫در‬ ِ‫جاهع‬ ‫در‬ ‫آى‬
.‫هیعازد‬ ‫فراّن‬ ‫را‬
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