Database

.......................... is a collection of data or information which is held together in an organised or logical way. Good example:

order details, school student records and customer details.

Stores all of the records related to a particular category.

• Database table

• Record

• Field

One specific piece of data about a particular item, for example hair colour, first name, street name

• Record

• Attribute

• Field

Stores all of the data about an entity (person, object or thing).

• Records

• Field

• Primary Key

Primary Key

• An attribute (field) or combinations of attributes (fields) which uniquely identifies a particular record in a table.

• Could be simple or compound

• Stores all of the data about an entity

Foreign Key

• a primary key from one table, included in another table to form a link.

• is any field in a table

• is a record in a table

A single table which stores all of the data held within that database.

• Relational database

• A flat file

Data redundancy refers to:

• Wasted data or duplication of data.

• The data held in more than one place in the database

• The correctness of the data over the lifetime of that data.

Data Consistency means:

• Any database transactions which are about to happen should see all previous changes implemented

• The correctness of the data over the lifetime of that data.

• Ensures that any constraints placed on the database, such as primary and foreign keys, are adhered to.

Data integrity refers to

• Data must be complete, accurate and consistent.

• the data is correct when it enters the database

• the correctness of the data over the lifetime of that data