Database Structure (Edexcel IGCSE Ict)

Spec point — 6.2.2

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