Database Structure (Edexcel IGCSE ICT)

Database structure

What is the structure of a database?

• A database is an organised collection of data

• A database is made up of either one or multiple tables which are made up of fields and records to organise how it stores data

• It allows easy storage, retrieval, and management of information

• A database is useful when working with large amounts of data

• A database can be stored on remote servers so multiple users can access it at the same time, useful for online systems

Fields, records and tables

• A field is a single piece of data in a table (column)

• An example of a field in the cars table is 'make'

• A record is complete set of fields on a single entity in a table (row)

• An example of a record in the cars table is '2, Mazda, MX5, Blue, 17995'

• A table is a complete set of records about the same subject/topic in a database

Relational databases

• A relational database is one that organises data into multiple tables 

• It uses keys to connect related data which:

  • reduces data redundancy

  • makes efficient use of storage

  • is easier to maintain

Primary & foreign keys

• A primary key is a unique field that can be used to identify a record in a table

• order_id is the primary key for the orders table

• customer_id is the primary key for the customers table

• A foreign key is a field in a table that refers to the primary key in another table.

• A foreign key is used to link tables and create relationships

• In the orders table customer_id is a foreign key - it links an order back to the customer that made the order in the customer table