Introduction to SQL and relational databases

SQL (Structured Query Language) is a standard programming language for managing and manipulating data stored in relational databases. A relational database is a type of database that organizes data into one or more tables, with each table consisting of rows and columns. The relationships between the data are established using keys.

SQL is used to interact with a relational database in order to perform tasks such as retrieving data, adding data, updating data, and deleting data. It is a powerful tool for working with large amounts of data and is widely used in data analytics, data science, business intelligence, and many other fields.

SQL is supported by most relational database management systems (RDBMS), such as MySQL, Oracle, Microsoft SQL Server, PostgreSQL, and SQLite. Each RDBMS has its own implementation of SQL and may have proprietary extensions, but the core SQL syntax and functionality are the same across all systems.

Relational databases are widely used because they provide a flexible and scalable way to store and manage data. They also have a well-defined structure and are optimized for fast data retrieval, making them ideal for applications that require fast access to large amounts of data.