RELATIONAL DATA MODEL

1. Data Dictionary

1.1. Provide detailed accounting of all table.

1.2. contain all the attribute name and characteristic for each table

1.3. contain metadata

2. CHARACTERISTIC

2.1. Name of each table must be distinct

2.2. each column represent attribute

2.3. all value in a collumn must conform to the same data format

2.4. each column has a specific range of value known as the attribute domain

2.5. the order of the row and column is immaterial to the DBMS

2.6. each table must have an attribute or a combination of an attribute that uniquely identify each row

2.7. each row represent a single entity occurrence within the entity set

2.8. a table perceive as a two dimensional structure composed of row and column

3. Data Redundancy

3.1. Data Anamolies

3.1.1. SUch anomalies can destroy the effectiveness of the database

3.2. Foreign keys

3.2.1. control data redundancy by using common attribute shared by tables

4. System Catalog

4.1. detailed system data dictionary that describe all object within the database.

5. RELATIONSHIP RULES

6. key's

6.1. composite key

6.1.1. Composed of more than one attribute

6.2. candidate key

6.2.1. A superkey without unnecessary attributes

6.3. superkey

6.3.1. Any key that uniquely identifies each row

6.4. attribute key

6.4.1. Any attribute that is part of a key

7. INTEGRITY RULES

7.1. Entity Integrity

7.1.1. Requirement

7.1.1.1. All primary key entries are unique, and no part of a primary key may be null

7.1.2. Purpose

7.1.2.1. Each row will have a unique identifiey, and foreign key values can properly reference primary key values

7.1.3. Example

7.2. Refenrence Integrity

7.2.1. Requirement

7.2.2. Purpose

7.2.3. Example