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Understanding the Differences Between SQL and NoSQL Databases


What is the difference between SQL and NoSQL?

Recently, I had an opportunity to be asked about this and could not explain it clearly. So, with the intention of enhancing my own learning as well, I decided to write this article. I hope it will be of help to those who are studying this field in the same way.

Databases are crucial tools for storing and retrieving information. There are various types of databases, with SQL and NoSQL being two major categories. In this blog post, I'll explain the key differences between these two types of databases.

Differences in Data Models

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SQL (Structured Query Language) databases use a table-based data model. Data is organized into rows and columns, with relationships managed using foreign keys. This is a characteristic feature of traditional relational databases.

On the other hand, NoSQL (Not Only SQL) databases provide a flexible data model. They support various data structures such as documents (e.g. Mongodb), key-value pairs (e.g. Redis), column families (e.g. Cassandra), and graphs (e.g. Neo4j). This allows for more natural storage of data.

Tip:What is Relational Database?

A relational database is a type of SQL database that uses a data model based on tables and relationships. Data is organized into rows and columns, with multiple tables linked through relationships. It supports ACID transactions, ensuring strict data integrity. Relational databases are well-suited for traditional business applications and systems where data consistency is critical.

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Differences in Scalability

SQL databases typically rely on vertical scaling, which means scaling up by adding more resources to a single server. This has inherent limits and may not be suitable for handling large volumes of traffic or data.

NoSQL databases are well-suited for horizontal scaling, achieved by distributing data across multiple servers. This makes them suitable for large-scale applications and high-traffic websites.

Differences in Transactions

SQL databases support ACID (Atomicity, Consistency, Isolation, Durability) transactions, ensuring data consistency and reliability. This is important for applications like financial transactions and reservation systems that require strict consistency.

NoSQL databases use the BASE (Basically Available, Soft state, Eventually consistent) model, prioritizing flexibility. Data consistency may not be guaranteed immediately, but it eventually becomes consistent.

Differences in Schema Flexibility

SQL databases typically have rigid schemas, and data must conform to these schemas. Schema changes can be challenging and time-consuming.

NoSQL databases offer schema flexibility, allowing you to easily add new fields or modify existing ones. This is advantageous for applications that evolve over time.


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By now, you should have a basic understanding of the differences between SQL and NoSQL databases. Consider the requirements of your project to determine which database type is the most suitable.

Thank you for reading!

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