SQL vs NoSQL Databases

One of the biggest myths about databases is that SQL databases use Structured Query Language (SQL) whereas NoSQL databases do not. It's better to think of SQL and NoSQL databases as relational and non-relational databases, since this tells us more about how they actually work.

Relational databases (SQL) organize data into separate tables, with each table representing a specific type of data. Imagine you have a Products table and a Suppliers table. Products table contains a SupplierID which is also present in Suppliers table. SupplierID is also called a ‘foreign key’ because it connects both the tables. This way, supplier information is stored just once, and we use SupplierID to piece everything together when needed.

Non-relational databases (NoSQL) take a different approach. Instead of using separate tables, they store data as individual documents or records. In our products example, each product record would look like this:

{
    "productId": "123",
    "name": "Laptop",
    "price": 999,
    "supplier": {
        "name": "Tech Supplies Inc",
        "address": "123 Tech Street",
        "contact": "john@techsupplies.com"
    }
}

This means some supplier information gets repeated across different products, but it's easier to access everything about a product in one go.

Each approach has its strengths. Relational databases are great when your data naturally has lots of relationships. They keep things organized and consistent, since you only need to update information in one place.

But relational databases can be slower in distributed systems where data is spread across multiple database servers. This is because getting all the related data might require checking multiple servers, which takes time.

Non-relational databases shine when you need quick access to all related data at once, since everything's stored together. They're often better for data that doesn't have many relationships - like social media posts, which mostly stand alone. The trade-off is that when you need to update something that's stored in multiple records, you have to update each copy, which can be complicated.