Relational Databases

Relational databases are the most well known.

They store data in tables. These tables have rows (records) and columns (fields).

Just like a spreadsheet.

Different tables can have relationships - hence the name.

These relationships are usually created by connecting tables based on a common field.

For example, a pet owners database might have two tables - Pets & Owners.

To relate a pet to its owner, the Owner table might have an ID column. The Pet table might have an Owner ID column. The connection is made by saying - the Owner ID column in the Pet table connects to the ID column in the Owner table.

Relational databases are great for data that is neat and structured.

They power a large majority of most software.

One of the challenges with relational databases is that they need planning. You need a pretty good idea of what your data is going to look like before you build the database.

Other database models have popped up to address this.