3.5. 4th Normal Form

  • No multi-valued dependencies

3.5.1. Problem

Table 3.17. astronauts

id (PK)

firstname

lastname

email

1

Melissa

Lewis

mlewis@nasa.gov

1

Melissa

Lewis

mlewis@gmail.com

2

Mark

Watney

mwatney@nasa.gov

3

Rick

Martinez

rmartinez@nasa.gov

Note, that Melissa has two emails: work email mlewis@nasa.gov and private email mlewis@gmail.com.

3.5.2. Solution

Table 3.18. astronauts

id (PK)

firstname

lastname

1

Melissa

Lewis

2

Mark

Watney

3

Rick

Martinez

Table 3.19. astronaut_emails

id (PK)

email

astronaut_id (FK)

1

mlewis@nasa.gov

1

2

mlewis@gmail.com

1

3

mwatney@nasa.gov

2

4

rmartinez@nasa.gov

3