Databases
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
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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;
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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;
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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;
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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';
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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
- 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