MySQL

MySQL is a database system used by many websites on the Internet. It is based on SQL. Many ways of doing things in SQL are similar in MySQL. The data is structured in tables in MySQL. And to extract data from the tables queries are used.

For example: SELECT id_number FROM main_database WHERE name='John'

This query will return the 'id_number' of the person named 'John' from the table named 'main_database'.