Lecture 5

Question 1

What are the three types of relationships within the relational model?

Answer 1

1:1, 1:M, M:N

These relationships define how entities interact within a relational database.

Question 2

Which relationship is considered the norm in any relational database design?

Answer 2

1:M

The 1:M (one-to-many) relationship is the most common type of relationship in relational databases.

Question 3

Which relationship should be rare in any relational database design?

Answer 3

1:1

A 1:1 (one-to-one) relationship indicates a very specific connection between two entities.

Question 4

How can M:N relationships be implemented in a relational model?

Answer 4

By changing them into two 1:M relationships

This conversion helps to avoid the complications associated with M:N relationships.

Question 5

What does a 1:M relationship signify?

Answer 5

One entity can be related to multiple instances of another entity

It is a foundational concept in relational database design.

Question 6

What could a 1:1 relationship imply about entity components?

Answer 6

Entity components were not defined properly

This might suggest that the two entities should actually be in the same table.

Question 7

What is a composite entity or bridge entity used for?

Answer 7

To avoid problems inherent to M:N relationships

It serves as a solution to facilitate the implementation of M:N relationships.

Question 8

What is the role of foreign keys in data redundancy control?

Answer 8

Control data redundancies by using common attributes shared by tables

Foreign keys help maintain relationships and integrity between tables.

Question 9

True or False: Data redundancy is always detrimental to a database.

Answer 9

False

Sometimes, data redundancy is necessary for certain database operations.

Question 10

What must each table row have in a relational database?

Answer 10

A primary key which uniquely identifies all attributes

This ensures that each record is distinct and retrievable.

Question 11

Fill in the blank: Tables can be linked by common attributes, thus the primary key of one table can appear as the _______ in another table.

Answer 11

foreign key

This establishes a relationship between the two tables.

Question 12

What are the three types of relationships that can be represented using ERDs?

Answer 12

1:1, 1:M, M:N

Entity-Relationship Diagrams (ERDs) visually depict these relationships.

Question 13

What is a crucial step in good database design?

Answer 13

Identifying appropriate entities and attributes and the relationships among the entities

Proper identification is key to effective database structure.