fundamentals of database systems questions and answers

https://www.facebook. com/Oxus20

Abdul Rahman Sherzad of 5

PART I – S ingle and Mult ip le 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



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



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 I I - Bas ic 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



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 I I I – ER to Relat ional 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



Part IV – Chal lenges :

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 Forum has 1 m

Forum

has 1 m main

sub

Figure 1 - One-to-Man

Figure 2 - Recursive

OXUS20 is a non-profit society with the aim of changing education for

the better by providing education and assistance to IT and computer

science professionals.

ت کوک آهزغ ارائ از طریك آهزغ پررغ تغییر تمیت ذف تا اتفاعی غیر اجوي یک 02آکعیض

.اظت کاهپیتر علم هتخصصاى

ایي دریا از ،تد اجويای فت ایي اظتعذاد تیاگر آب تریي رد آظیای هیا ک دظت هج آى ترگرفت از دریای آه پر اجويام ایي

ؼوالی ظرزهیي تاظتای افغاعتاى را آتیاری هیکذ ک ایي حالت دریا ذف ارای خذهات داه ای کي پاهیر ظرچؽو گرفت هارای

هیذذ.را اعکاض اجوي

هحصالى داػ هاظة ترای تجلی اظتعذادا تراگیختي خاللیت ؼکفایی علوی فضایایجاد در ظر دارد تا خذهاتی هاذ 02آکعیض

تر گیری از هؽارکت آا در افراد خالق، خث عاللوذؼاظایی کارتردی، ادهذ ظاختي فعالیت ای فق تراه علوی پصاى،

علم عصری تکالشی اتؽار ؽریات علوی تخصصی پتى ا دیگر هراکس آهزؼی جاهع وچى تلیذ ارتمای فضای علوی

آى در جاهع در راظتای رچ تتر ؼذى زهی تذریط، تحمیك پصػ را ای رظیذى ت آهال افراد جاهع هعلهاتی را ت ؼکل هثر

را فران هیعازد.

Follow us on Facebook,

https://www.facebook.com/Oxus20

https://www.facebook.com/Oxus20

fundamentals of database systems questions and answers

Education