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What are the main features of SQL databases?

Created on 2025-03-25 17:51:48
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SQL databases, also known as relational databases, are characterized by their ability to organize data into tables with rows and columns. Here are the main features:

  1. Structured Data: SQL databases store data in a structured format, using tables with predefined schemas. Each table has columns that define the type of data, and rows represent individual records.

    • Example: A database for an e-commerce site might have a table called "Products" with columns for "ProductID," "ProductName," "Price," and "StockQuantity."

  2. ACID Compliance: SQL databases follow the principles of Atomicity, Consistency, Isolation, and Durability (ACID), ensuring reliable transactions and data integrity.

    • Example: If a transaction to update a product's stock fails, the database will ensure that no partial changes are made, maintaining consistency.

  3. SQL Query Language: They use Structured Query Language (SQL) for querying and manipulating data. SQL allows for complex queries involving multiple tables and conditions.

    • Example: A query to find all products priced between $10 and $50 would use SQL statements to filter and retrieve the relevant data.

  4. Scalability: SQL databases can scale vertically (by upgrading hardware) or horizontally (by adding more servers), though horizontal scaling can be more complex.

    • Example: A growing e-commerce site might scale its SQL database by adding more servers to handle increased traffic and data storage needs.

  5. Relationships: They support relationships between tables, such as one-to-one, one-to-many, and many-to-many, enabling complex data structures.

    • Example: A "Customers" table might have a one-to-many relationship with an "Orders" table, where each customer can have multiple orders.

  6. Security: SQL databases offer robust security features, including encryption, access controls, and audit logs, to protect data from unauthorized access.

    • Example: A database might use SSL encryption for data in transit and implement role-based access control to restrict who can view or modify data.

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