SQL (pronounced “sequel”) is an English-like language used to ask questions of a database. For example, you might ask a database of people to: Select address from people where surname = ’bloggs’

However, the term SQL now refers to more than just the query language – it also tends to be used for the database server software that understands the SQL and manages the database. Popular SQL Servers include Microsoft SQL, Oracle, PostgreSQL and MySQL.

SQL was intended to simplify access to information by making it easier to write complex questions in a way that the computer can understand. However, although it’s true that many users can write simple SQL, many real-world questions are in fact quite complex and require complex SQL. For example: “show me the top three salespeople grouped by division” is a relatively complex question, and most non-programmers are unlikely to be able to write it.

SQL-based database systems have become the dominant approach to storing information, although it’s important to note that SQL is not a very strong standard. Each SQL Server implements its own version of the language and moving SQL queries between database systems can in some cases require significant changes.