Databases are fundamental for storing and managing data. Two broad categories exist: SQL (relational) and NoSQL (non-relational) databases.
SQL databases are based on a structured schema and use Structured Query Language (SQL) for defining and manipulating data.
NoSQL databases provide flexible schemas and are designed for specific data models like key-value, document, column-family, or graph.
| Aspect | SQL | NoSQL |
|---|---|---|
| Schema | Fixed, predefined | Flexible or schema-less |
| Scaling | Vertical scaling | Horizontal scaling |
| Transactions | Strong ACID compliance | Often eventual consistency |
| Query Language | SQL | Varies (MongoDB uses JSON queries, Cassandra uses CQL) |
| Use Cases | Traditional apps with complex joins | Large-scale, distributed apps |
For more info, see SQL vs NoSQL Databases.