Database & SQL: Basic Concepts
Target Version: SQL:2023 Standard (ANSI/ISO) Official Documentation: PostgreSQL Documentation / MySQL Documentation
1. What is a Database?
A Database is a systematically organized collection of data. Multiple users or applications can simultaneously access it to store, modify, and retrieve data.
2. Introduction to SQL (Structured Query Language)
SQL is a special-purpose programming language designed for managing data in Relational Database Management Systems (RDBMS).
- Standardization: Commonly used across most RDBMS (MySQL, PostgreSQL, Oracle, SQL Server).
- Declarative Language: Describes "What" to get, rather than "How" to get it.
3. Relational Database (RDBMS)
Data is managed in the form of Tables, where each table consists of rows and columns. Complex data is managed efficiently by defining relations between tables.
- Major RDBMS:
- MySQL: The most widely used open-source DB.
- PostgreSQL: A DB known for its powerful features and standard compliance.
- SQLite: A lightweight, file-based DB.