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SQLvsNoSQL
What is the difference between SQL and NoSQL databases?
Updated 2 min read7 differences
In short
SQL databases keep data in related tables with a fixed schema, while NoSQL databases use flexible models like documents or key-value pairs that scale out.
SQL
Structured Query Language
SQL is the standard language for working with relational databases, used to create tables and to insert, query, update, and delete the data stored in them.
Read the page on SQLNoSQL
Not Only SQL
NoSQL is a family of databases that store data in models other than relational tables, such as documents, key-value pairs, wide columns, or graphs.
Read the page on NoSQLSQL and NoSQL compared
| Aspect | SQL | NoSQL |
|---|---|---|
| Data model | Tables of rows and columns linked by keys | Documents, key-value pairs, wide columns or graphs |
| Schema | Fixed schema defined before data is written | Flexible schema; records can differ in shape |
| Query language | Standard SQL with joins, grouping and subqueries | Database-specific APIs or SQL-like languages |
| Relationships | Joins across tables are a core feature | Related data is usually embedded or duplicated |
| Consistency | Strong ACID transactions by default | Often eventual consistency; transaction support varies |
| Scaling | Usually scales up; scaling out needs replicas or sharding | Designed to scale out across many servers |
| Best for | Structured data with clear relationships, like orders and payments | Huge volumes, changing structures or simple lookups at scale |
The difference, explained
SQL databases, also called relational databases, store data in tables of rows and columns and are queried with SQL (Structured Query Language). NoSQL is an umbrella term for databases that use other data models, such as documents, key-value pairs, wide columns or graphs, and they usually come with their own query APIs.
The core difference is how structure is enforced. A relational database checks every row against a schema defined up front and links tables with foreign keys and joins, which keeps data consistent. Many NoSQL databases let each record have its own shape and store related data together, which makes schema changes and horizontal scaling (spreading data across many machines) simpler, at the cost of fewer built-in guarantees across records.
The two are often used together. A typical system keeps orders and payments in a relational database, a key-value store for caching and sessions, and a document database for fast-changing content. The lines have also blurred: many relational databases now store and index JSON, and several NoSQL databases support multi-document transactions.
A common misconception is that NoSQL means 'no SQL at all' or that it is always faster. The name is usually read as 'not only SQL', some NoSQL systems offer SQL-like query languages, and speed depends on the access pattern: a well-indexed relational database is very fast for most workloads.
Which one should you use?
Choose SQL when…
- Your data has clear relationships and must stay consistent.
- You need complex queries, reports or ad hoc joins.
- Transactions such as payments or stock updates must be all-or-nothing.
- Your schema is fairly stable and well understood.
Choose NoSQL when…
- Your data structure changes often or varies between records.
- You need to spread huge volumes of reads and writes across many servers.
- Your access pattern is simple, like fetching a record by its key.
- You store naturally nested data, such as product catalogs or user profiles.
Reading users and their order totals
// SQL: data lives in separate tables; a join combines them
const result = await db.query(
"SELECT u.name, o.total FROM users u " +
"JOIN orders o ON o.user_id = u.id " +
"WHERE u.active = true"
);// Document database: orders are embedded inside each user
const users = await db
.collection("users")
.find({ active: true }, { projection: { name: 1, "orders.total": 1 } })
.toArray();Readers ask
Is NoSQL faster than SQL?
Not in general. NoSQL databases can be faster for simple key-based lookups at very large scale, but a well-indexed relational database is fast for most applications, and complex queries are often easier and quicker in SQL.
Can you use SQL and NoSQL together?
Yes. Many systems keep core business data in a relational database and add NoSQL stores for caching, sessions, search or high-volume event data. This mix is often called polyglot persistence.
Should a beginner learn SQL or NoSQL first?
SQL is usually the better first step. Tables, keys and joins appear almost everywhere, and knowing them makes it easier to understand what NoSQL databases trade away.