Relational vs. Non-Relational Database: Pros & Cons

A database is a set of data held in a computer that can be accessible in various manners. There are two main database types: Relational & Non-Relational. So, what’s the difference?

A relational database is structured, meaning the data is organized in tables. Many times, the data within these tables have relationships with one another, or dependencies. A non relational database is document-oriented, meaning, all information gets stored in more of a laundry list order. Within a single construct, or document, you will have all of your data listed out.

SQL Databases (Relational)

SQL is short for Structured Query Language, basically meaning a very firm way of sorting through data in the form of tables, columns, and rows. How is data structured in an SQL database? The table itself would be made up really of one variable or object that we would be looking through. The column would represent the data point itself that needs to be stored and the row is a record of the data points per column.

For example, if you are looking to sort data regarding what the weather is at a certain time of the day during a certain day, it would be structured as the following:

• Table: Weather
• Columns: Days of the Week
• Rows: Time of Day
• Data Points: Degrees Fahrenheit

In this structure, all queries would be related to this table and the structure of the table would allow for easy sorting, filtering, computations, etc. If we ever need to establish a connection between tables, say, you want to know what the weather was at a certain time and relate that to a baseball game’s predicted score, then what we do is create what is called a key. This key allows for connections to be made between two or more tables to solidify associations between the two.

Some popular SQL database systems include:

• Oracle
• Microsoft SQL Server
• PostgreSQL
• MySQL
• MariaDB

NoSQL Databases (Non-Relational)

In contrast to a relational database, a NoSQL database is one that is less structured/confined in format, and thus, allows for more flexibility and adaptability. If you are going to be dealing with a dataset that isn’t clearly defined, meaning not organized or structured, you likely won’t have the luxury of establishing defined tables and relationships amongst the dataset.

For example, Facebook Messenger uses a NoSQL database, because the information that is being gathered isn’t structured enough to be segmented into tables and define relationships between each other. With tons of unstructured information, it needs to be held in a non-relational database. Think of the information as being stored on one large word document. Everything is there. As more information gets entered, the document gets longer. If you want to find and pull data, you have to in essence ‘control/command + F’ and search for the data itself.

Some popular NoSQL databases include:

• MongoDB
• Google Cloud Firestore
• Cassandra
• Redis
• Apache HBase
• Amazon DynamoDB

Final Showdown: Pros and Cons of Relational and Non-Relational Databases

Now we answer the question you’re really looking for. Which type of database should you use? Well, there are some questions you should ask yourself that are outlined below. If you answer yes to the relational questions, then use a SQL database. If you answer yes to the non-relational questions, then use a NoSQL database.

Pros of a Relational Database

1. Data is easily structured into categories.
2. Your data is consistent in input, meaning, and easy to navigate.
3. Relationships can be easily defined between data points.

Pros of a Non-Relational Database

1. Data is not confined to a structured group.
2. You can perform functions that allow for greater flexibility.
3. Your data and analysis can be more dynamic and allow for more variant inputs.

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