Chapter 18: The REA Data Model

Question 1

3 steps to implementing an REA diagram

Answer 1

1. create a table for each distinct entity entity in the diagram and for each many-to-many relationship
2. Assign attributes to appropriate tables
3. use foreign keys to implement one-to-one and one-to-many relationships.

Question 2

One-to-One relationships

Answer 2

show 2 entities on REA

Question 3

Many-to-Many relationships

Answer 3

results in more than one record for each entity

Question 4

3 types of anomaly

Answer 4

update
insert
delete

Question 5

Update anomaly

Answer 5

causes problems when every occurrence of a data item is not updated
I

Question 6

Insert Anomaly

Answer 6

causes difficulties (sometimes impossibility) to insert new data into a table without violating the basic integrity rules

Question 7

Delete Anomaly

Answer 7

involves unintended loss of data that occurs when deleting a record in a table

Question 8

Concatenated key

Answer 8

two columns together as the primary key

Question 9

Entity Integrity Rule

Answer 9

each table MUST have a primary key and the primary key must have value- cant search data if null (blank)

Question 10

Referential Integrity

Answer 10

Foreign key data MUST match Primary Key or be null (blank)

Question 11

Steps of Implementing an REA Diagram in a relational Database

Answer 11

1. create a table for each entity
2. Create a table for each many-to-many relationship
3. examine tables with a one-to-one relationship-combine if appropriate
4. Identify the attributes and assign the primary key for each table
5. Implement relationships using foreign keys