Relational Data Model

1. Keys

1.1. Primary key(PK)

1.1.1. Cannot contain null values

1.2. Foreign Key(FK)

1.2.1. column(s) whose values must match the values in a candidate key of another table

1.3. Candidate key

1.3.1. Minimal Superkey

1.4. Superkey

1.4.1. Composed of more than one attribute

1.5. composite Key

1.5.1. A multiple-attribute key

1.6. Nulls

1.6.1. Special value meaning value unknown or inapplicable

2. Intergrity Rules

2.1. Entity Intergrity

2.1.1. Primary Keys

2.2. Referential Intergrity

2.2.1. Foreign Keys

3. Definition

3.1. Digital database whose organization based on relational model of data

3.2. The various software system used to maintain relational databases are known as a relational database management system

3.3. all data is represented in terms of tuples, grouped into relations

3.4. proposed be E. F. Codd 1970

4. Relationship

4.1. 1:1 Relationship

4.2. M:N Relationship

5. Table

5.1. Each table row represent a single entity occurance within the entity set

5.2. Each table column represent an atrribute and each column has a distinct name

5.3. Each row/column intersection represent a single data value

5.4. A table is perceived as a two-dimensional structure composed of rows and column