Relational Databases

In this step, we’ll take a closer look at how to build a relational database and what to consider when planning the schema.

Normalisation

Normalisation is the process of organising data in a database. A common goal is to reduce the number of columns within a single table and have multiple tables that link and relate to each other.

Traditionally, this process goes through three steps of transformation.

First normal form

In this step, we remove repeating groups by:

• Eliminating repeating groups in individual tables
• Creating a separate table for each set of related data
• Identifying each set of related data with a unique primary key.

Second normal form

We remove partial dependencies within the data, by:

• Creating separate tables for sets of values that apply to multiple records
• Relating these tables with a foreign key, which links to a primary key in a different table.

Third normal form

Finally, we eliminate transitive dependencies by eliminating fields that don’t depend on the key.

In the next step, we’ll explore how to work with Azure SQL Database using Query Editor.