Databases are management systems that allow storing, organizing and managing data efficiently.

What are Databases?

Databases are management systems that allow storing, organizing, querying and managing data in a structured and efficient manner.

Database Types

By Model

  • Relational: Relational databases
  • NoSQL: NoSQL databases
  • Document: Document databases
  • Graph: Graph databases

By License

  • Proprietary: Proprietary software
  • Open Source: Open source
  • Commercial: Commercial software
  • Free: Free software

Management Systems

Microsoft SQL Server

  • Features: Enterprise database
  • License: Proprietary
  • Platform: Windows, Linux
  • Features: Microsoft integration

PostgreSQL

  • Features: Advanced relational database
  • License: Open Source
  • Platform: Multi-platform
  • Features: Extensibility, SQL standards

MySQL

  • Features: Popular relational database
  • License: Dual (GPL/Commercial)
  • Platform: Multi-platform
  • Features: Ease of use, performance

Oracle Database

  • Features: Enterprise database
  • License: Proprietary
  • Platform: Multi-platform
  • Features: Scalability, performance

Configuration

PostgreSQL

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-- Create database
CREATE DATABASE mydb;

-- Create user
CREATE USER myuser WITH PASSWORD 'mypassword';

-- Grant permissions
GRANT ALL PRIVILEGES ON DATABASE mydb TO myuser;

-- Connect to database
\c mydb

MySQL

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-- Create database
CREATE DATABASE mydb;

-- Create user
CREATE USER 'myuser'@'localhost' IDENTIFIED BY 'mypassword';

-- Grant permissions
GRANT ALL PRIVILEGES ON mydb.* TO 'myuser'@'localhost';
FLUSH PRIVILEGES;

SQL Server

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-- Create database
CREATE DATABASE mydb;

-- Create user
CREATE LOGIN myuser WITH PASSWORD = 'mypassword';

-- Create database user
USE mydb;
CREATE USER myuser FOR LOGIN myuser;

-- Grant permissions
ALTER ROLE db_owner ADD MEMBER myuser;

Queries

Basic

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-- Select data
SELECT * FROM users WHERE age > 18;

-- Insert data
INSERT INTO users (name, email, age) VALUES ('John', 'john@example.com', 25);

-- Update data
UPDATE users SET age = 26 WHERE name = 'John';

-- Delete data
DELETE FROM users WHERE age < 18;

Advanced

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-- Joins
SELECT u.name, p.title FROM users u JOIN posts p ON u.id = p.user_id;

-- Aggregations
SELECT COUNT(*), AVG(age) FROM users GROUP BY city;

-- Subqueries
SELECT * FROM users WHERE id IN (SELECT user_id FROM posts WHERE created_at > '2024-01-01');

-- Views
CREATE VIEW active_users AS SELECT * FROM users WHERE last_login > NOW() - INTERVAL '30 days';

Use Cases

Web Applications

  • User Management: User management
  • Content Management: Content management
  • E-commerce: E-commerce
  • Analytics: Data analysis

Companies

  • ERP: ERP systems
  • CRM: CRM systems
  • HR: Human resources systems
  • Finance: Financial systems

Big Data

  • Analytics: Data analysis
  • Machine Learning: Machine learning
  • Data Warehousing: Data warehouses
  • Business Intelligence: Business intelligence

Best Practices

Design

  • Normalization: Data normalization
  • Indexing: Index usage
  • Constraints: Integrity constraints
  • Documentation: Schema documentation

Performance

  • Query Optimization: Query optimization
  • Indexing: Indexing strategies
  • Partitioning: Data partitioning
  • Caching: Query caching

Security

  • Access Control: Access control
  • Encryption: Data encryption
  • Backup: Regular backups
  • Monitoring: Security monitoring
  • DBAaaS - Database as a service
  • DLP - Data loss prevention
  • SIEM - System that monitors databases
  • SOAR - Database automation
  • EDR - Database protection
  • Firewall - Network protection for databases
  • VPN - Secure connection to databases
  • VLAN - Network segment for databases
  • Logs - Database logs
  • Dashboards - Database visualization
  • Metrics - Database measurement
  • CISO - Role that oversees databases
  • Incident Response - Process that includes databases
  • DRP - Recovery plan that includes databases

References