Introduction to SQL: What Is SQL?

SQL (Structured Query Language) is a language for relational database.
It allows:

- The creation of databases and tables.
- The search of data in the base.
- Updating data.
- Management of rights of users.

The main commands are:
- CONNECT to etablish a connection to a database.
- CREATE to create a new database or a table.
- INSERT to add data.
- SELECT to make a search in the content.

It is possible to write SQL procedural programs with iterations and conditions.

The best known version on the Web is MySQL, a free implementation that is used particularly with PHP, but also SQL is the language of many other database software such as PostGreSQL, Oracle, DB2, Access and SQL Server...

SQL commands are close to the natural language, it was the goal of the language the principles of which were posed by Edgar F. Codd and applied by IBM SEQUEL (Structured Query Language English), then renamed SQL.
But the first commercial version based on Sequel was made by Relational Software, named Oracle now.

ISO SQL-92 or SQL-2 was developed in 1992 and is commonly used. But new standards have succeeded it, not necessarily implemented on all software. ISO SQL: 2006 can manage XML files, including importing XML data in a database or export its content in XML.

You can access a database by sending commands as it is done in PHP, or with a visual software such as phpMyAdmin running on the server or locally through Wamp Server, as well as many other such local servers.

In this tutorial, we will use MySQL with PHP as phpMyAdmin interface.