Lession#1 - ERD

What is the meaning of cardinality in an ERD?

• The number of tables in the database

• The number of attributes in an entity

• The number of relationships between entities

• The number of instances of one entity related to another

Which of the following represents a one-to-many relationship in ERD notation?

• A line with '1' on both sides

• A line with 'M' on one side and 'N' on the other

• A line with '1' on one side and 'N' or a crow’s foot on the other

• A line with 'N' on both sides

Which of the following best describes a many-to-many relationship?

• One instance of entity A is related to multiple instances of entity B, and vice versa

• One instance of entity A is related to exactly one instance of entity B

• Multiple instances of entity A are related to one instance of entity B

• One instance of entity A is related to no instances of entity B

What is the minimum cardinality in a relationship?

• The maximum number of entities that can be involved in the relationship

• The number of attributes involved in the relationship

• The minimum number of entities that must participate in the relationship

• The number of relationships an entity can have

What is the primary purpose of an Entity-Relationship Diagram (ERD)?

• To represent the structure of a relational database

• To list all the files used in a database system

• To model the flow of data between processes

• To represent user interactions in a system

In ERD notation, how are entities typically represented?

• Circles

• Rectangles

• Diamonds

• Ovals

What is the purpose of a relationship in an ERD?

• To describe the attributes of an entity

• To indicate connections between entities

• To define the primary key of an entity

• To represent the number of rows in a database table

In ERD notation, what symbol is used to represent an attribute?

• Rectangle

• Diamond

• Oval

• Arrow

Which of the following is used to represent a weak entity in an ERD?

• A rectangle with a double border

• A diamond with a double border

• An oval with a dashed line

• A rectangle with a single border

How is a primary key attribute represented in an ERD?

• Inside a diamond

• With an underline

• Inside a rectangle with a double border

• With a dashed line