Chapter 18: The REA Data Model Flashcards

1
Q

3 steps to implementing an REA diagram

A
  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.
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2
Q

One-to-One relationships

A

show 2 entities on REA

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3
Q

Many-to-Many relationships

A

results in more than one record for each entity

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4
Q

3 types of anomaly

A

update
insert
delete

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5
Q

Update anomaly

A

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

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6
Q

Insert Anomaly

A

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

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7
Q

Delete Anomaly

A

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

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8
Q

Concatenated key

A

two columns together as the primary key

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9
Q

Entity Integrity Rule

A

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

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10
Q

Referential Integrity

A

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

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11
Q

Steps of Implementing an REA Diagram in a relational Database

A
  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
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