Database Design for Mere Mortals Ch. 10

Question 1

State two major reasons why a relationship is important.

Answer 1

— Establishes a connection between a pair of tables that are logically related to each other
— Helps to refine table structures and minimize redundant data
— The mechanism that enables you to draw data from multiple table simultaneously

Question 2

Name the three types of relationships.

Answer 2

1. One-to-one
2. One-to-many
3. Many-to-many

Question 3

Which relationship will pose the most problems?

Answer 3

Many-to-many

Question 4

State two problems you could possibly encounter with a many-to-many relationship.

Answer 4

— Will be tedious and somewhat difficult for you to retrieve information from one of the tables
— One of the tables will contain a large amount of redundant data
— Duplicate data will exist within both tables
— Will be difficult to insert, update, and delete data

Question 5

What is a self-referencing relationship?

Answer 5

A relationship that exists between the records within a given table

Question 6

How do you begin the process of identifying the relationship among the tables in the database?

Answer 6

By creating a matrix of all the tables

Question 7

What are the two types of questions you can ask to help you identify existing relationships?

Answer 7

Associative and contextual

Question 8

What shorthand symbol do you use to designate a one-to-many relationship in the table matrix?

Answer 8

1:N

Question 9

How do you determine what type of relationship officially exists between each pair of tables in the matrix?

Answer 9

Using formulas that correspond to the three relationship-type definitions

Question 10

How do you establish a one-to-many relationship?

Answer 10

By taking a copy of the primary key from the table primary table and incorporating it within the table structure on the second table, where it becomes a foreign key

Question 11

True or False: Retrieving information from tables with a self-referencing relationship can be tedious and somewhat difficult.

Answer 11

True

Question 12

How do you establish a self-referencing many-to-many relationship?

Answer 12

As you would a dual-table, many-to-many relationship — with a linking table

Question 13

How do you refine the foreign keys in the database?

Answer 13

By ensuring that each one complies with the Elements of a Foreign Key

Question 14

What two elements categories must you modify for a foreign key’s field specification?

Answer 14

The General Elements and Logical Elements

Question 15

What is the function of a deletion rule?

Answer 15

Determines what your RDBMS should do when you place a request to delete a given record in the parent table of the relationship

Question 16

What two types of participation can you designate for a table?

Answer 16

Mandatory and Optional

Question 17

What does the degree of participation indicate?

Answer 17

The minimum number of records that a given table must have associated with a single record in the related table

Question 18

When does a relationship attain relationship-level integrity?

Answer 18

After you’ve verified that it is properly established and its characteristics are suitably set