MSDS7330- Homework 2 Solved

assignment 2.

1)        The Entity-Relationship model is

a)     a way to graphically represent the logical relation-ships of entities in a database.

b)    a way to graphically represent the data in adatabase.

c)     a way to graphically represent only the constraintsin a database.

d)    a way to graphically represent strong entity setsbut not weak entity sets.

2)        In the Entity-Relationship model, to what does an entity refer (or represent)?

a)     The organization in which the model is created.

b)    A distinctly identifiable item, thing or object.

c)     A particular instance of data.

d)    A database schema.

3)        An entity set is

a)     a collection of databases.

b)    a collection of relationships connecting a singleentity to many other entities.

c)     a collection of entities of the same type that sharethe same properties.

d)    a collection of attribute values that are the sameacross all entities.

4)        Entities can be associated with one another by using which of the following?

a)     Entities

b)    Attributes

c)     Identifiers

d)    Relationships

5)        In a one-to-many relationship, the entity that is on the many side of the relationship is called what type of entity?

a)     parent

b)    child

c)     instance

d)    subtype

6)        In an Entity-Relationship model, attributes may be which of the following?

a)     simple

b)    composite

c)     multi-valued

d)    All of the above.

e)    None of the above.

7)        In an Entity-Relationship model, relationship sets are represented by which of the following?

a)     Rectangles

b)    Diamonds

c)     Lines

d)    Ovals

8)        Directed lines from a relationship set to all of its related entity sets indicates which type of relationship?

a)     One-to-one

b)    One-to-many

c)     Many-to-one

 2016 Sohail Rafiqi, Ph.D. All Rights Reserved.
d)    Many-to-many

9)        Consider the entity set instructor containing the attributes ID, name, deptName and salary with ID as the primary key and the entity set department containing the attributes deptName, building and budget with deptName as the primary key. In order to represent the relationship between instructor and department we need to do which of the following?

a)     Nothing. The relationship is properly representedby the deptName attribute in the instructor entity set.

b)    Add a one-to-one relationship instructorDepartment that explicitly relates instructor to department and leave the entity sets unchanged.

c)     Add a one-to-one relationship instructorDepartment that explicitly relates instructor to department and remove the deptName attribute from the instructor entity set.

d)    Add a one-to-many relationship instructorDepartment that explicitly relates instructor to department and remove the deptName attribute from the instructor entity set.

10)    Which of the following is NOT a basic element of the Chen version of the E-R model?

a)     Entities

b)    Attributes

c)     Relationships

d)    All of the above.

e)    None of the above.

11)    An attribute that names or identifies entity instances is a(n):

a)     entity

b)    attribute

c)     identifier

d)    relationship

12)    In an Entity-Relationship model, double lines connecting

2

an entity set to a relationship set indicates which of the following?

a)     Two constraints on the entity set.

b)    Every entity participates in up to two relationshipsof the given type.

c)     Some entities participate in more than one relation-ship of the given type.

d)    Every entity participates in at least one relationshipof the given type.

13)    Relationship sets can be used to directly represent which of the following?

a)     Entity attributes.

b)    Relationships between attribute values.

c)     Relationship between multiple entity sets.

d)    All of the above.

e)    None of the above.

14)    In the Entity-Relationship model, attributes may be represented as which of the following?

a)     The only name within the top of a double sectionedrectangle.

b)    Ovals

c)     Names above lines

d)    The only name within a diamond.

15)    In crow’s foot notation of the Entity-Relationship model, consider the simple ER model of entity E1 and entity E2 connected by a relationship line R where the line ends in a crow’s foot at E1 but ends simply as a line at E2. This represents which of the following relationship types?

a)     One-to-one

b)    Many-to-one

c)     One-to-many

d)    Many-to-many