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Database Basics Explained: SQL, NoSQL, Tables, and Queries

Tap a term to see what it means.

Database

A systematically organized collection of data, stored so a computer can easily search and manage it.

Table

A unit of data storage within a database, structured in rows and columns β€” similar in structure to a spreadsheet.

SQL (Relational) Database

Stores data in a predefined, table-based structure, and is typically used for systems like banking or e-commerce where accuracy and consistency matter most.

NoSQL Database

Stores data flexibly without a fixed table structure, making it well suited for services that need to quickly process varied types of data.

Query

A command used to request that a database retrieve or modify specific data.

Primary Key

A value assigned to uniquely identify each row in a table β€” the same value can never be duplicated.

Backup

The task of separately copying and safely storing a database's contents to protect against data loss.

Nearly Every Service Has a Database Behind It

From a shopping site's product listings to social media posts to bank transaction records, most of the services we use every day work by storing and retrieving information in a database. Knowing the basic terms helps you understand how these kinds of services actually function.

SQL and NoSQL Suit Different Needs

Neither approach is universally better β€” the right choice depends on whether your data has a clear, consistent structure (favoring SQL) or needs flexible structure and fast scaling (favoring NoSQL).

Frequently Asked Questions

Which is better, SQL or NoSQL?

Neither is inherently superior β€” generally, SQL is chosen when data structure is clear and consistency matters most, while NoSQL is chosen when flexible structure and fast scaling are the priority.

Why can't a primary key have duplicate values?

Because a primary key's job is to uniquely identify each piece of data, a duplicate value would make it impossible to tell which record is being referred to, breaking the accuracy of the data.