What is SQL injection?

SQL injection is a code injection technique used to attack data-driven applications, in which malicious SQL statements are inserted into an entry field for execution (e.g. to dump the database contents to the attacker). SQL injection exploits security vulnerabilities in an application's software, for example, when user input is improperly filtered for string literal escape characters embedded in SQL statements or user input is not strongly typed and thereby unexpectedly executed. SQL injection is often used to attack web applications but can also be used to attack any type of SQL database.