SQL injection is a form of attack that takes advantage of applications that generate SQL queries using user-supplied data without first checking or pre-processing it to verify that it is valid. The objective is to deceive the database system into running malicious code that will reveal sensitive information or otherwise compromise the server. By modifying the expected Web application parameters, an attacker can submit SQL queries and pass commands directly to the database. Many webpages take input from users, such as search terms, feedback comments or username and password and use them to build a SQL query which is passed to the database.