If user input is inserted without modification into an SQL query, then the application becomes vulnerable to SQL injection, like in the following example: $unsafe_variable = $_POST[‘user_input’]; mysql_query(“INSERT INTO `table` (`column`) VALUES (‘$unsafe_variable’)”); That’s because the user can input something like value’); DROP TABLE table;–, and the query becomes: INSERT INTO `table` (`column`) VALUES(‘value’); DROP … Continue reading How can I prevent SQL-injection in PHP?