IT3 Database Terminology

A group of tables linked together by primary and foreign keys

• Primary key

• Relational database

• Flat file database

This is a real-world object that data is being stored about (eg; Student, customer, lesson, product etc).

• Entity

• Attribute

• Relationship

• Table

A single item of data representing a fact about an entity (eg; first name, age, address)

• Attributes

• Entites

• Relationships

How entities are related to each other (eg; Customer> order> Product)

• Relationships

• Primary key

• Entities

• Attributes

This is unique and is used to identify a record in a table. Other fields in the table depend on it.

• Foreign key

• Primary key

• Attribute

• Relationship

A field of one table which is also a primary key of another table. It is used to establish links between entities in the database.

• Primary key

• Foreign key

• Attribute

• Relationships

This is where the same data has exactly the same value and formatting throughout, normally because it is only stored once.

• Data consistency

• Data redundancy

• Data integrity

This is where you store an item of data more than once and it is repeated unnecessarily.

• Data redundancy

• Data integrity

• Data reiteration

• Data consistency

The correctness or accuracy of the data.

• Data redundancy

• Data integrity

• Data consistency

• Data independence

This is where the data and the applications it uses are independent. New applications can be developed to access the data without changing the data.

• Data independence

• Data integrity

• Data redundancy

• Data consistency