SQL (Structured Query Language) - The Smart Notes
Introduction to SQL
**SQL (Structured Query Language)** is a standard language used for managing and manipulating databases. It allows users to store, retrieve, update, and delete data efficiently. SQL is widely used in relational database management systems (**RDBMS**) like **MySQL, PostgreSQL, SQL Server, and Oracle**.
Key Features of SQL
- Data Querying: Use SELECT statements to fetch specific data.
- Data Manipulation: Perform INSERT, UPDATE, and DELETE operations.
- Data Definition: Create and modify database structures using CREATE, ALTER, and DROP commands.
- Joins & Relationships: Combine data from multiple tables using INNER JOIN, LEFT JOIN, and RIGHT JOIN.
- Normalization: Organize data to eliminate redundancy and ensure integrity.
- Indexes & Views: Improve query performance and simplify complex queries.
- Transactions: Ensure database consistency using COMMIT and ROLLBACK.
Applications of SQL
SQL is used in various fields, including:
- Web Development: Backend database management for websites.
- Data Analysis: Extract and analyze large datasets.
- Business Intelligence: Generate reports and dashboards.
- Cybersecurity: Manage access control and data encryption.
- Cloud Computing: SQL databases in AWS, Google Cloud, and Azure.