Principle of Least Privilege

The principle of least privilege can be used to improve the security of any computer system. It's a basic but important principle that is often overlooked. The principle is as follows:

A user (or process) should have the lowest level of privilege required to perform his assigned task.

It applies in MySQL as it does elsewhere. For example, to run queries from the Web, a user does not need all the privileges to which "root" has access. You should therefore create another user who has only the necessary privileges to access the database you just created.

Excerpt from PHP and MySQL Web Development page 223